Park Record Media Center

This photo taken on Monday, May 26, 2014 and provided by Dalton Barlow, shows a tornado heading towards Watford City, N.D. A National Weather Service team is headed to western North Dakota Tuesday, to assess the strength of the tornado that injured at least nine people, including a 15-year-old girl who suffered critical injuries, and damaged or destroyed 15 trailers at a workers' camp in the heart of the state's booming oil patch. (AP Photo/Dalton Barlow) ( North Dakota Tornado )

This photo taken on Monday, May 26, 2014 and provided by Jill Helmuth, shows a tornado touching down on a reach before heading towards Watford City, N.D. (AP Photo/Jill Helmuth) ( APTOPIX North Dakota Tornado )

This Monday, May 26, 2014 photo taken from video provided by Dan Yorgason shows debris flying through the air from a tornado passing through a worker's camp near Watford City, N.D., in the heart of the state's booming oil patch. (AP Photo/Dan Yorgason) ( North Dakota Tornado )

Debris from a destroyed trailer is scattered Tuesday morning, May 27, 2014, after a tornado in Watford City, N.D. Authorities say at least eight trailers were destroyed Monday evening when the twister tore through a camp where oil field workers stay. Nine people were injured, including a 15-year-old girl critically. (AP Photo/Josh Wood) ( North Dakota Tornado )

In this photo taken on Monday, May, 26, 2014, and provided by Neal Shipman, residents look for personal belongings in damaged trailers after a tornado hit an oil worker's camp in Watford City, ND. (AP Photo/McKenzie County Farmer, Neal A. Shipman) ( North Dakota Tornado )

The remnants of a trailer, right, and other trailers, left, relatively undamaged, Tuesday, May 27, 2014, after a tornado in Watford City, N.D. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )

People search through wreckage Tuesday, May 27, 2014, after a tornado in Watford City, N.D. Authorities say at least eight trailers were destroyed Monday evening when the twister tore through a camp where oil field workers stay. Nine people were injured, including a 15-year-old girl critically. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )

In this Monday, May, 26, 2014 photo provided by Neal Shipman, residents look for personal belongings in damaged trailers after a tornado hit an oil worker's camp in Watford City, ND. (AP Photo/Courtesy McKenzie County Farmer, Neal A. Shipman) ( North Dakota Tornado )

This photo taken on Monday, May, 26, 2014, and provided by Neal Shipman, shows damaged trailers after a tornado hit an oil worker's camp in Watford City, ND. (AP Photo/McKenzie County Farmer, Neal A. Shipman) ( North Dakota Tornado )

People search through wreckage Tuesday, May 27, 2014, after a tornado in Watford City, N.D. Authorities say at least eight trailers were destroyed Monday evening when the twister tore through a camp where oil field workers stay. Nine people were injured, including a 15-year-old girl critically. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )

Debris is scattered Tuesday, May 27, 2014, after a tornado in Watford City, N.D. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )

A McKenzie County Sheriff talks on a phone among scatterd debris Tuesday morning, May 27, 2014, after a tornado in Watford City, N.D. (AP Photo/Josh Wood) ( North Dakota Tornado )

A man walks past trailers Tuesday, May 27, 2014 in Watford City, N.D, that were destroyed by a tornado the night before. (AP Photo/Josh Wood) ( North Dakota Tornado )

People clean up debris Tuesday, May 27, 2014, after a tornado in Watford City, N.D. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )

The remnants of a child's toy thrown out rests in a the field a few hundred meters west of the trailer park Tuesday, May 27, 2014, after a tornado in Watford City, N.D. Authorities say at least eight trailers were destroyed Monday evening when the twister tore through a camp where oil field workers stay. Nine people were injured, including a 15-year-old girl critically. (AP Photo/Williston Herald, Tyler Bell) ( North Dakota Tornado )