Elite men runners leave the start line in the 118th running of the Boston Marathon Monday, April 21, 2014, in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
Race fans from left, Andrew Lembecke, of Chicago, Brandon Petrich of Fargo, N.D, Marlene Youngblood of Louisville, Ky, and Bill Januszewski cheer near the finish line at the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty) ( Boston Marathon )
The Elite Men's division starts the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903531 )
Mike Poitras, of Dracut, Mass., wears the slogan "Boston Strong" on his head near the finish line before the start of 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa) ( Boston Marathon )
Mobility-impared runners David Abel, left, Juli Windsor, and Scott Rigsby compete in the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Michael Dwyer) ( APTOPIX Boston Marathon )
Mackenzie Petermeier, of Baxter, Iowa, who will be a guide for a blind runner, waits to board a bus in Boston to the starting line in Hopkinton, Mass., for the 118th Boston Marathon Monday, April 21, 2014. (AP Photo/Matt Rourke) ( Boston Marathon )
Elite men runners leave the start line in the 118th running of the Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
A Boston Police K-9 officer and his dog patrol with a National Guardsman, rear right, along Commonwealth Avenue near the finish line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty) ( Boston Marathon )
The Elite Women's division starts the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903547 )
A race fan waves the American flag and a banner bearing the slogan "Boston Strong" as runners compete in the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Michael Dwyer) ( Boston Marathon )
The elite men's runners compete near the start of the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Steven Senne) ( APTOPIX Boston Marathon )
The elite men's runners race near the start of the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Michael Dwyer) ( Boston Marathon )
Fans hold "Boston Strong" flags prior to the start of the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903153 )
Runners Meb Keflezighi, and Ryan Hall, right, of the United States, wish each other well before the start of 118th Boston Marathon Monday, April 21, 2014, in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
Two police officers look on from a rooftop near the start area of the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903175 )
The elite men's runners compete near the start of the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Steven Senne) ( Boston Marathon )
Volunteers look on during a flyover by the Massachusetts Army National Guard members of C Company, 3rd of
the 126th General Support Aviation Battalion before the start of the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903245 )
Members of the Push Rim Wheelchair division start the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903267 )
Volunteers look on as Wave 1 starts the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903283 )
Police on bicycles ride the route before the start of the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485903397 )
Sgt. Daniel M. Clark sings the national anthem prior to the start of the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903587 )
Tom Grilk, Executive Director of the Boston Athletic Association, looks on during the national anthem prior to the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903667 )
Runners in the first wave of 9,000 cross the start line of the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( APTOPIX Boston Marathon )
Ernst Van Dyk, of South Africa, breaks the tape to win the men's wheelchair division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Kimberley Garcia of Boston poses with the slogan "Boston Strong" on her leg in Boston before boarding a bus to the starting line in Hopkinton, Mass., to compete in the 118th Boston Marathon Monday, April 21, 2014. (AP Photo/Matt Rourke) ( Boston Marathon )
Marla Fogelman, right, hangs a banner on the second floor over Marathon Sports store, the site of the first bomb blast in 2013, before the start of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa) ( Boston Marathon )
Governor Deval Patrick speaks to the media after the start of the Mobility Impaired division of the 118th Boston Marathon on April 21, 2014 in Hopkinton, Massachusetts. (Photo by Alex Trautwig/Getty Images) ( 485903609 )
Dick Hoyt pushes his son Rick Hoyt, both from Holland, Mass., center, as they compete in the wheelchair division of the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. They are competing in their 32nd Boston Marathon and have said this will be their last. (AP Photo/Michael Dwyer) ( Boston Marathon )
Mobility-impaired runners gather at the start line for a moment of silence before the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( APTOPIX Boston Marathon )
Race fans cheer runners as they start the 118th Boston Marathon Monday, April 21, 2014. in Hopkinton, Mass. (AP Photo/Michael Dwyer) ( APTOPIX Boston Marathon )
Boston Police officers on bicycles ride across the finish line before during 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Men's Wheelchair winner Ernst Van Dyk of South Africa, comes down Boylston Street on his way to winning the Men's Push Rim Wheelchair division of the 118th Boston Marathon in Boston, Massachusetts April 21, 2014 . AFP PHOTO / Timothy A. CLARY/AFP/Getty Images ( 529125686 )
Race officials wire the electronics for the start line before the 118th Boston Marathon begins Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
Anthony Bisenti cleans the finish line before the running of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty) ( Boston Marathon )
Meb Keflezighi, of the United States, leads Josphat Boit, also from the United States, passed Wellesley College during the 118th Boston Marathon Monday, April 21, 2014 in Wellesley. (AP Photo/Mary Schwalm) ( Boston Marathon )
Mobility-impaired runner Juli Windsor gets hi-fives from students lining Wellesley College during the 118th Boston Marathon Monday, April 21, 2014 in Wellesley. (AP Photo/Mary Schwalm) ( Boston Marathon )
Meb Keflezighi, of San Diego, Calif., hoists his trophy after winning the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
The girls of Wellesley College cheer as father and son Dick Hoyt and Rick Hoyt, from Holland, Mass., compete in the 118th Boston Marathon, Monday, April 21, 2014 in Wellesley, Mass. (AP Photo/Mary Schwalm) ( Boston Marathon )
Tatyana McFadden, of the United States, breaks the tape to win the women's wheelchair division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa) ( APTOPIX Boston Marathon )
Meb Keflezighi, of San Diego, Calif., celebrates after winning the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Runners place their hands over their hearts during a singing of the National Anthem at the beginning of the Boston Marathon on April 21, 2014 in Hopkington, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485905715 )
A runner gives a high five at the beginning of the Boston Marathon on April 21, 2014 in Hopkington, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485905733 )
Runners place their hands over their hearts during a singing of the National Anthem at the beginning of the Boston Marathon on April 21, 2014 in Hopkington, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485905735 )
Ernst van Dyke celebrates after he won the men's wheelchair division of the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485906475 )
Tatyana McFadden celebrates as she wins the women's wheelchair division of the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485906777 )
Tatyana McFadden celebrates as she wins the women's wheelchair division of the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485906781 )
Tatyana McFadden celebrates as she wins the women's wheelchair division of the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485906783 )
Rita Jeptoo of Kenya celebrates after winning the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485907575 )
Meb Keflezighi of the United States reacts after winning the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485911589 )
Meb Keflezighi of the United States celebrates with the trophy after winning the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485912063 )
Shalane Flanagan runs in the Boston Marathon on April 21, 2014 in Boston, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485912255 )
Shalane Flanagan runs in the Boston Marathon on April 21, 2014 in Boston, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485912265 )
Race fans alongside a "Boston Strong" slogan, watch the 118th Boston Marathon Monday, April 21, 2014 along the race course to Boston. (AP Photo/Steven Senne) ( Boston Marathon )
Ernst Van Dyk, of South Africa, celebrates with his trophy after winning the men's wheelchair division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( APTOPIX Boston Marathon )
Rita Jeptoo, of Kenya, hoists the trophy after winning the women's division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Shalane Flanagan leads Buzunesh Deba, of Ethiopia, and Mare Dibaba, of Ethiopia, and the elite pack past Wellesley College during the 118th Boston Marathon Monday, April 21, 2014 in Wellesley. (AP Photo/Mary Schwalm) ( Boston Marathon )
Elite runners lead by Dennis Kimetto, of Kenya, and Markos Geneti, of the United States, pass Wellesley College during the 118th Boston Marathon Monday, April 21, 2014 in Wellesley. (AP Photo/Mary Schwalm) ( Boston Marathon )
Participants in the wheelchair division of the 118th Boston Marathon start their race Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
Meb Keflezighi, of San Diego, Calif., celebrates his victory in the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa) ( Boston Marathon )
Boston Marathon bombing hero Carlos Arredondo tries on a victor's wreath near the finish line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Participants in thewheelchair division of the 118th Boston Marathon begin their race Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia) ( Boston Marathon )
Boston Mayor Martin Walsh places a wreath on Meb Keflezighi, of San Diego, Calif., after Keflezighi won the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
A "Boston Strong" sticker is seen on the prosthetic leg of Boston Marathon bombing survivor Marc Fucarile after he threw out the ceremonial first pitch before the baseball game between the Boston Red Sox and the Baltimore Orioles at Fenway Park in Boston Monday, April 21, 2014. (AP Photo/Winslow Townson) ( APTOPIX Orioles Red Sox Baseball )
Boston Marathon husband and wife bombing survivors Patrick Downes and Jessica Kensky, who each lost a leg in last year's bombings, roll across the finish line in the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( APTOPIX Boston Marathon )
Rita Jeptoo, of Kenya, kisses the trophy after winning the women's division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Meb Keflezighi, of San Diego, Calif., runs the final few blocks before winning the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Steven Senne) ( Boston Marathon )
Men's Elite division winner Meb Keflezighi(L) of the US and Women's Elite Division winner Rita Jeptoo of Kenya pose for photographers after running the 118th Boston Marathon in Boston, Massachusetts April 21, 2014 . AFP PHOTO / Timothy A. CLARY/AFP/Getty Images ( 529127863 )
Men's Elite division winner Meb Keflezighi of the US crosses the finish line during the 118th Boston Marathon in Boston, Massachusetts April 21, 2014 . AFP PHOTO / Timothy A. CLARY/AFP/Getty Images ( 529127909 )
Boston Marathon bombing survivors Adrianne Haslet-Davis, left, and Jeff Bauman share a hug near the finish line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa) ( APTOPIX Boston Marathon )
Boston Marathon bombing hero Carlos Arredondo cheers for runners near the finish line of the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Runners make their way down Boylston Street to receive their medals after competing in the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Jared Wickerham/Getty Images) ( 485928061 )
Carlos Arredondo talks with a runner who participated in the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485928447 )
A runners holds an American flag during the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) *** BESTPIX *** ( 485928459 )
Runners participate at the finish line in the 2014 B.A.A. Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485928483 )
;BOSTON, MA - APRIL 21: A man with "We're Back!" written on his chest limps by after finishing the Boston Marathon on April 21, 2014 in Boston, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485928529 )
Runners wear space blankets after finishing the Boston Marathon on April 21, 2014 in Boston, Massachusetts. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485928535 )
Meb Keflezighi of the United States celebrates with the tophy after winning the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485928745 )
Two soldiers cross the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485928851 )
Handcycle division competitors cross the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485929793 )
Celeste Corcoran (C) gives high fives while she is helped by her daughter Sydney Corcoran (R) after finishing the Boston Marathon on April 21, 2014 in Boston, Massachusetts. Both women were victims of last year's Boston Marathon Bombings. Today marks the 118th Boston Marathon; security presence has been increased this year, due to two bombs that were detonated at the finish line last year, killing three people and injuring more than 260 others. (Photo by Andrew Burton/Getty Images) ( 485934805 )
First responder Carlos Arredondo cheers on finishers of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937521 )
Runners approach the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937535 )
Runners approach the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937565 )
Runners approach the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937581 )
Runners approach the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937583 )
Runners approach the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937591 )
Two runners hug after crossing the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937595 )
A runner approaches the finish line of the 118th Boston Marathon on April 21, 2014 in Boston, Massachusetts. (Photo by Jim Rogash/Getty Images) ( 485937597 )
Runners pass discarded cups after a water station during the 118th Boston Marathon Monday, April 21, 2014 in Wellesley, Mass. (AP Photo/Mary Schwalm) ( Boston Marathon )
Women display placards and cheer near Wellesley College along the route of the 118th Boston Marathon, Monday, April 21, 2014, in Wellesley, Mass. (AP Photo/Steven Senne) ( Boston Marathon )
Devin Parker, of Hanover, N.H., kisses John T. Heineman, of Iowa City, Iowa, as they cross the finish line of the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Bombing survivor Jeff Bauman, center, cheers for Meb Keflezighi who won the 118th Boston Marathon, Monday, April 21, 2014, in Boston. Bauman suffered traumatic injuries in the bombings near the finish line last year. At right is his fiancee Erin Hurley. (AP Photo/Elise Amendola) ( Boston Marathon )
Kyle Marshall, of Phoenix, collapses at the finish line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Elise Amendola) ( Boston Marathon )
Meb Keflezighi, of San Diego, Calif., celebrates his victory in the 118th Boston Marathon, Monday, April 21, 2014, in Boston.(AP Photo/Elise Amendola) ( Boston Marathon )
Boston Marathon bombing survivor Jeff Bauman, left, greets Carlos Arredondo near the finish line of the the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Charles Krupa) ( Boston Marathon )
Race fans cheer runners at mile marker 26 of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty) ( Boston Marathon )
Hugo R. Gonzalez Sr., left, of Miami, and Kyle Brumbaugh, right, of Dayton Ohio, assist Skye Taylor, of Columbus, Ohio, after she collapsed approaching the finish of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty) ( Boston Marathon )
Runners make their way to the finish line during the 118th Boston Marathon in Boston, Massachusetts April 21, 2014 . AFP PHOTO / Timothy A. CLARY/AFP/Getty Images ( 529128125 )
Runners mill about on Boylston Street street after completing of the 118th Boston Marathon in Boston, Massachusetts April 21, 2014. Meb Keflezighi became the first American male athlete since Greg Meyer in 1983 to win the Boston Marathon on Monday while Kenya's Rita Jeptoo won her second women's title in a row and third overall. AFP PHOTO / Timothy A. CLARY/AFP/Getty Images ( 529128907 )