Sue Ogrocki/AP
A woman carries her child through a field near the collapsed Plaza Towers Elementary School in Moore, Okla., May 20, 2013.
Brennan Linsley/AP
An American flag blows in the wind at sunrise atop the rubble of a destroyed home a day after a tornado moved through Moore, Okla., May 21, 2013.
Brett Deering/Getty Images
Dana Ulepich searches inside a room left standing at the back of her house destroyed after a powerful tornado ripped through Moore, Okla., May 20, 2013.
Brennan Linsley/AP
A member of a security team helps guard an area of rubble from a destroyed residential neighborhood, one day after a tornado moved through Moore, Okla., May 21, 2013.
Paul Hellstern/The Oklahoman/AP
Teachers carry children away from Briarwood Elementary school after a tornado destroyed the school in south Oklahoma City, May 20, 2013.
AP Photo Sue Ogrocki
A fire burns in the Tower Plaza Addition in Moore, Okla., following a tornado Monday, May 20, 2013. A tornado as much as a mile wide with winds up to 200 mph roared through the Oklahoma City suburbs Monday, flattening entire neighborhoods, setting buildings on fire and landing a direct blow on an elementary school.
Steve Gooch/AP
This aerial photo shows the remains of homes hit by a massive tornado in Moore, Okla., Monday May 20, 2013.
AP Photo Sue Ogrocki
A boy is pulled from beneath a collapsed wall at the Plaza Towers Elementary School following a tornado in Moore, Okla., Monday, May 20, 2013.
NASA/Getty Images
A storm system that generated an EF4 tornado is captured at 19:40 UTC on May 20, 2013 over Moore, Okla.
Brett Deering/Getty Images
Damaged vehicles are piled up in front of the Moore Warren Theater after a powerful tornado ripped through Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
A child is carried from the rubble of the Plaza Towers Elementary School following a tornado in Moore, Okla., Monday, May 20, 2013.
Sarah Phipps/AP
People react in front of the Plaza Towers Elementary school in Moore following a deadly tornado, May 20, 2013.
Oklahoma County Sheriff
Scared, but this little pup survived in Moore, Okla., Monday, May 20, 2013. A tornado as much as a mile wide with winds up to 200 mph roared through the Oklahoma City suburbs, flattening entire neighborhoods, setting buildings on fire and landing a direct blow on an elementary school.
Brett Deering/Getty Images
Cars marked with an orange 'X', denoting they had been checked for occupants, are piled up in what was the front entrance to the damaged Moore Medical Center after a powerful tornado ripped through Moore, Okla., May 20, 2013.
Brett Deering/Getty Images
Dana Ulepich looks at the debris from her house destroyed after a powerful tornado ripped through Moore, Okla., May 20, 2013.
CBS News
This dramatic photo of a giant twister in the rear-view mirror was taken by a driver leaving Moore, Okla., as a series of tornadoes, up to a mile wide in total, caused devastation across Oklahoma City's suburbs on May 20, 2013.
Steve Gooch/AP
This aerial photo shows the remains of homes hit by a massive tornado in Moore, Okla., May 20, 2013.
Brett Deering/Getty Images
People walk through a damaged area near the Moore Warren Theater after a powerful tornado ripped through Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
A child is pulled from the rubble of the Plaza Towers Elementary School in Moore, Okla., and passed along to rescuers Monday, May 20, 2013. A tornado as much as a mile wide with winds up to 200 mph roared through the Oklahoma City suburbs, flattening entire neighborhoods, setting buildings on fire and landing a direct blow on an elementary school.
Steve Gooch/AP
This aerial photo shows the remains of homes hit by a massive tornado in Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
Onlookers watch as children are pulled from the rubble of the Plaza Towers Elementary School following a tornado in Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
A woman carries her child through a field near the collapsed Plaza Towers Elementary School in Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
A woman carries an injured child to a triage center near the Plaza Towers Elementary School in Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
A child calls to his father after being pulled from the rubble of the Tower Plaza Elementary School following a tornado in Moore, Okla., May 20, 2013.
CBS News
Screen grab of damage in Moore, Oklahoma from massive tornado that swept through on Monday afternoon.
Oklahoma County Sheriff
Scenes of devastation in Moore, Okla., after a massive series of tornadoes tore through the are on May 20, 2013.
CBS News
A building flattened by Monday's massive tornado is seen in Moore, Okla.
AP Photo Sue Ogrocki
A boy is pulled from beneath a collapsed wall at the Plaza Towers Elementary School following a tornado in Moore, Okla., May 20, 2013.
AP Photo Sue Ogrocki
Moore police dig through the rubble of the Plaza Towers Elementary School following a tornado in Moore, Okla., May 20, 2013.
Oklahoma County Sheriff
A U.S. flag lays among debris in Moore, Okla., May 20, 2013 following a tornado up to a mile wide which swept through the Oklahoma City suburbs.
Oklahoma County Sheriff
Rescue personnel fold a U.S. flag in Moore, Okla., May 20, 2013 following a tornado up to a mile wide which swept through the Oklahoma City suburbs.
CBS
Screen grab of damage in Moore, Okla. from massive tornado that swept through on Monday afternoon.
CBS News
Screen grab of damage in Moore, Okla. from massive tornado that swept through on Monday afternoon.
CBS News
A massive tornado ripped through the Oklahoma City suburb of Moore, May 20, 2013.
CBS News
Screen grab of damage in Moore, Okla. from massive tornado that swept through on Monday afternoon.
KWTV
A tornado rips through the Oklahoma City area Monday afternoon, May 20, 2013.
KWTV
Screen grab of damage in Moore, Okla. from massive tornado that swept through on Monday afternoon.
CBS News
Another very large tornado was seen touching down near Oklahoma City, Okla. on Monday afternoon, May 20, 2013.
AP Photo/Sue Ogrocki
Seven-year-old Katrina Ash watches with her mother, Amber Ash, as heavy equipment is brought into their tornado damaged neighborhood near Dale, Okla., May 19, 2013. Residents were not being allowed into the neighborhood as search and rescue operations continued.
AP Photo Sue Ogrocki
Seven-year-old Katrina Ash holds a doll as she waits with her grandfather, Michael Bowen, after a tornado ripped through their neighborhood near Dale, Okla., May 19, 2013. Residents are not being allowed back into the neighborhood as search and rescue efforts take place.
CBS News
Debris is kicked up by a twister, one of several tornadoes that struck parts of the nation's midsection, May 19, 2013.
Sue Ogrocki/AP
Maeghan Hadley, of One Day Ranch pet rescue, checks a kitten pulled from the rubble of a mobile home destroyed by Sunday's tornado in the Steelman Estates Mobile Home Park, near Shawnee, Okla., May 20, 2013.
Sue Ogrocki/AP
A resident searches through the rubble of his mobile home, in the Steelman Estates Mobile Home Park, destroyed by Sunday's tornado, near Shawnee, Okla., May 20, 2013. The tornado that slammed into Oklahoma on Sunday is now blamed for two deaths. Authorities say two men in their 70s have been found dead in or near a mobile home park outside of Shawnee.
Sue Ogrocki/AP
Members of the Chickasaw Nation search and rescue group dig through debris, May 20, 2013, to locate a kitten buried in the rubble of a mobile home destroyed in Sunday's tornado, in the Steelman Estates Mobile Home Park, near Shawnee, Okla.
AP Photo/Sean Murphy
Residents of Edmond, Okla., survey storm damage from a tornado that hit their neighborhood Sunday, May 19, 2013.
AP Photo/Sean Murphy
People survey damage from a tornado that hit Edmond, Okla., May 19, 2013.
Getty Images Brett Deering
Volunteers help clean out Jean McAdams' mobile home near Shawnee, Okla., after it was overturned by a tornado May 20, 2013.
Getty Images Brett Deering
An electrical pole lies on a Pottawatomie County road near Shawnee, Okla., after a tornado touched down there, May 20, 2013.
CBS News
One of several tornadoes which touched down in the U.S. Midwest, May 19, 2013, afflicting severe damage in central Oklahoma and Wichita, Kan. One person was killed near Shawnee, Okla., and 21 injuries were reported throughout the state.
Getty Images Brett Deering
Volunteers help with cleanup of Tom and Ronda Clark's property near Shawnee, Okla., after it was damaged by a tornado May 20, 2013.
Getty Images Brett Deering
A piece of corrugated tin is draped over a power line near Shawnee, Okla., after a tornado swept through the area on May 20, 2013.
Getty Images Brett Deering
Candice Lopez (L) and Stephanie Davis help clean debris from Thelma Cox's mobile home near Shawnee, Okla., after it was destroyed by a tornado May 20, 2013.
Bryan Bedford (via Twitter)
A twister approaches the home of Bryan Bedford in south Oklahoma City, May 20, 2013.