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Workers who had sheltered in place exit the Navy Yard following a shooting at the Navy Yard in Washington on September 16, 2013. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 13 lives, including the gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. "At this hour, it appears that we have at least 12 fatalities," Washington DC police chief Cathy Lanier told a press conference. SAUL LOEB/AFP/Getty Images ( 522951332 )

Employees from the Navy Yard complex depart a gathering point for reuniting family members that was set up inside Nationals Park in the wake of the Navy Yard shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180787721 )

A woman wrapped in a Red Cross blanket leaves a gathering point for reuniting family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180793032 )

School children leave Richard Wright school after the lockdown was lifted in the area of the US Navy yard ,September 16, 2013 in Washington, DC. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 12 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. "At this hour, it appears that we have at least 12 fatalities," Washington DC police chief Cathy Lanier told a press conference. MLADEN ANTONOV/AFP/Getty Images ( 522949823 )

A woman hugs her child while reuniting at a gathering point for family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180792666 )

A man and woman embrace while reuniting at a gathering point for family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180793037 )

A US Park Police helicopter patrols over the US Navy Yard September 16, 2013 in Washington,DC. An unidentified gunman opened fire at the US Navy Yard in Washington on Monday and wounded several people including two police officers, officials reported. Police and FBI agents descended on the area in force as helicopters buzzed overhead, amid reports the shooter was armed with an assault rifle and was on the loose in the complex. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, the Washington Post and other media reported. At one point a police helicopter hovering over the complex lowered a man down by rope into the compound. Police blocked off intersections around the Navy Yard as military troops in uniform stood guard at street corners. AFP PHOTO/Paul J. RichardsPAUL J. RICHARDS/AFP/Getty Images ( 522941468 )

A police boat patrols near the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013, in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard, and officials said six people were killed and as many as 10 were wounded, including a law enforcement officer. (AP Photo/ Evan Vucci) ( Shooting Military Building )

A police helicopter circles around above the Washington Navy Yard after a shooting rampage happened September 16, 2013 in Washington, DC. Police believe there to be as many as two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180776465 )

An unmarked helicopter approaches for a landing on the Route 295 bridge, now a police landing zone, over the Ancostia River near the US Navy Yard on September 16, 2013 in Washington,DC. An unidentified gunman opened fire at the US Navy Yard in Washington on Monday and wounded several people including two police officers, officials reported. Police and FBI agents descended on the area in force as helicopters buzzed overhead, amid reports the shooter was armed with an assault rifle and was on the loose in the complex. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, the Washington Post and other media reported. At one point a police helicopter hovering over the complex lowered a man down by rope into the compound. Police blocked off intersections around the Navy Yard as military troops in uniform stood guard at street corners. PAUL J. RICHARDS/AFP/Getty Images ( 522942777 )

Police tactical units leave after responding to a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage at the Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. "We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured," she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. SAUL LOEB/AFP/Getty Images ( 522947466 )

A Emergency Response Team vehicle arrives to the scene where a gunman was reported at the Washington Navy Yard in Washington, on Monday, Sept. 16, 2013. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Jacquelyn Martin) ( Shooting Military Building )

Police tactical units leave after responding to a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage at the Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. "We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured," she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. SAUL LOEB/AFP/Getty Images ( 522947460 )

People come out from a building with their hands up after a shooting happened at the Washington Navy Yard September 16, 2013 in Washington, DC. Police believe there to be as many as two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180773589 )

People come out from a building with their hands up after a shooting happened at the Washington Navy Yard September 16, 2013 in Washington, DC. Police believe there to be as many as two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180773026 )

People exit a building with their hands above their heads as police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. SAUL LOEB/AFP/Getty Images ( 522943739 )

A U.S. Park Police helicopter with a person in the rescue basket, flies over a building at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning. (AP Photo/Susan Walsh) ( Shooting Military Building )

District of Columbia Police Chief Cathy Lanier briefs reporters on the shooting at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. Standing to the right of Lanier is District of Columbia Mayor Vincent Gray. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning (AP Photo/Susan Walsh) ( Shooting Military Building )

This booking photo provided by the Fort Worth Police Department shows Aaron Alexis, arrested in September, 2010, on suspicion of discharging a firearm in the city limits. Alexis is suspected to be the shooter at the Washington D,C. Navy Yard Monday, Sept. 16, 2013. (AP Photo/ Fort Worth Police Department) ( Navy Yard Shooting )

Debris sits in front of the last known address of Aaron Alexis Monday, Sept. 16, 2013, in Fort Worth, Texas. Police have identified Alexis as the gunman in Monday's shooting rampage at at the Washington Navy Yard in Washington. Mayor Vincent Gray said at a news conference Monday afternoon that Alexis was among the dead. (AP Photo/LM Otero) ( Shooting Military Building )

U.S. Capitol Police personnel keep watch on the East Plaza of the Capitol as the investigation continues to the shooting at the nearby Washington Navy Yard Monday, Sept. 16, 2013, in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said six people were killed and as many as 10 were wounded, including a law enforcement officer. (AP Photo/J. Scott Applewhite) ( Shooting Military Building Capitol )

U.S. Capitol Police personnel keep watch on the East Plaza of the Capitol as the investigation continues to the shooting at the nearby Washington Navy Yard Monday, Sept. 16, 2013, in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning. (AP Photo/J. Scott Applewhite) ( Shooting Military Building )

President Barack Obama speaks in the South Court Auditorium on the White House complex, Monday, Sept. 16, 2013, in Washington. Before speaking about the economy Obama commented on the WashingtonNavy Yard shooting. (AP Photo/Carolyn Kaster) ( Obama Shooting Military Building )

President Barack Obama arrives to speak in the South Court Auditorium on the White House complex, Monday, Sept. 16, 2013, in Washington. Before speaking about the economy Obama commented on the Navy Yard shooting. (AP Photo/Carolyn Kaster) ( Shooting Military Building )

Two men embrace at a gathering point for family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180793065 )

Secretary of the Navy Ray Mabus (C) visits a gathering point for reuniting family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images) ( 180793064 )

Media and emergency response personnel gather outside the US Navy Yard September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. MLADEN ANTONOV/AFP/Getty Images ( 522946413 )

A U.S. Park Police helicopter continues a search pattern above the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013 in Washington. (AP Photo/ Evan Vucci) ( Shooting Military Building )

A U.S. Park Police helicopter continues a search pattern above the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013 in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer. (AP Photo/ Evan Vucci) ( Shooting Military Building )

Law enforcement personnel are seen outside the gate into the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer. (AP Photo/Susan Walsh) ( Shooting Military Building )

A US Park Police helicopter patrols over the US Navy Yard September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. PAUL J. RICHARDS/AFP/Getty Images ( 522943104 )

A police officer inspects vehicles with his canine at a parking lot outside the Washington Navy Yard as he responds to a shooting September 16, 2013 in Washington, DC. Police believe there to be two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180769673 )

Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. SAUL LOEB/AFP/Getty Images ( 522943129 )

District of Columbia Mayor Vincent Gray speaks during a press conference on M Street, SE near the Washington Navy Yard on September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. MANDEL NGAN/AFP/Getty Images ( 522943857 )

Police walk on a residential street near the Washington Navy Yard on September 16, 2013 in Washington, DC. One gunman has been killed and up to two more may still be at large after a shooting rampage at the US Naval base in Washington on Monday that left "multiple victims" dead, the city's police chief said. "We have one shooter that we believe involved in this that is deceased," said Washington police chief Cathy Lanier. "The big concern for us right now is that we potentially have two other shooters that we have not located at this point." MANDEL NGAN/AFP/Getty Images ( 522944112 )

An armored personnel carrier speeds down M Street, SE away from the Washington Navy Yard on September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. MANDEL NGAN/AFP/Getty Images ( 522943121 )

A U.S. Park Police helicopter flies over a building at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. President Barack Obama is mourning what he called "yet another mass shooting" in the United States that he says took the life of American patriots. (AP Photo/Susan Walsh) ( Shooting Military Building )

Armed police prepare to enter the Washington Navy Yard as they respond to a shooting in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Navy yard. (AP Photo/Manuel Balce Ceneta) ( Shooting Military Building )

A woman talks on the phone after she walked out of a building on M Street, SE near the Washington Navy Yard on September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing "multiple" victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. "We believe there were multiple deaths," a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. MANDEL NGAN/AFP/Getty Images ( 522943061 )

A Park Police helicopter hovers above snipers on the roof of a building at the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images) ( 180765202 )

Police boats patrol the water outside a building at the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images) ( 180768969 )

Law enforcement personnel respond to a reported shooting at the Washington Navy Yard September 16, 2013 in Washington, DC. Police believe there to be two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180769222 )

Law enforcement personnel respond to a reported shooting at the Washington Navy Yard September 16, 2013 in Washington, DC. Police believe there to be two shooters who killed several people and wounded others in an incident that put parts of the city on lockdown. (Photo by Alex Wong/Getty Images) ( 180769223 )

Armed ATF agents stage on the 11th Street Bridge adjacent to the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images) ( 180765862 )

Police and firefighters respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said."There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522940243 )

Law enforcement personnel respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC. According to the latest news report several people were shot with the shooter still possibly active. (Photo by Alex Wong/Getty Images) ( 180740161 )

A helicopter lifts a person off the roof as police respond to the report of a shooting at the Navy Yard in Washington, Dc on September 16, 2013. Departures have been halted at Washington's Reagan National Airport due to a shooting at the US Navy Yard, an official said Monday. Chris Paolino, a spokesman for the airport, said inbound aircraft are still landing and that the airport remains open to passengers. "We can confirm that the FAA (Federal Aviation Administration) has halted aircraft departures from Reagan National due to an active law enforcement incident at the Washington Navy Yard," Paolino told AFP via email. Several people have been wounded in the shooting at the nearby US Navy Yard in Washington, authorities said. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522940648 )

Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said."There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522940174 )

Emergency vehicles and law enforcement personnel respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC. According to the latest news report, several people were shot with the shooter still possibly active. (Photo by Alex Wong/Getty Images) ( 180728651 )

Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said."There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522939482 )

Law enforcement personnel respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC. According to news reports several people were shot with a shooter still active. (Photo by Alex Wong/Getty Images) ( 180740544 )

Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said."There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522939475 )

A general view shows police and first responder activity on M Street, SE near the Washington Navy Yard on September 16, 2013 in Washington, DC. An unidentified gunman opened fire at the US Navy Yard in Washington on Monday and wounded several people including two police officers, officials reported. Police and FBI agents descended on the area in force as helicopters buzzed overhead, amid reports the shooter was armed with an assault rifle and was on the loose in the complex. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, the Washington Post and other media reported. At one point a police helicopter hovering over the complex lowered a man down by rope into the compound. Police blocked off intersections around the Navy Yard as military troops in uniform stood guard at street corners. MANDEL NGAN/AFP/Getty Images ( 522941178 )

Two DC Metro Police officers respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC. According to the latest news report several people were shot with the shooter still possibly active. (Photo by Alex Wong/Getty Images) ( 180728676 )

Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said."There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. SAUL LOEB/AFP/Getty Images ( 522939479 )

Police work the scene on M Street, SE in Washington near the Washington Navy Yard on Monday, Sept. 16, 2013. The U.S. Navy says one person is injured after a shooting at a Navy building in Washington. Police and emergency crews gathered Monday morning outside the Naval Sea Systems Command Headquarters building, where the shooting was reported. (AP Photo/Jacquelyn Martin) ( US Shooting Military Building )