A man looks through debris of a home belonging to a friend along Kings Manor in Moore, Okla., on Tuesday, May 21, 2013. A massive tornado swept through the south Oklahoma City suburb Monday afternoon. (AP Photo)

Urban Search and Rescue workers comb through debris Tuesday, May 21, 2013, at Plaza Towers Elementary School in Moore, Okla (AP Photo)

Rescue workers comb through the wreckage of a tornado in Moore (AP Photo)

Storm clouds build in the distance beyond tornado-ravaged homes (AP Photo)

Residents pass a destroyed car as they walk through a tornado-ravaged neighborhood (AP Photo)

A woman is pulled out from under tornado debris at the Plaza Towers School (AP Photo)

A tornado moves past homes in Moore, Okla. (AP Photo)

A monstrous tornado as much as half a mile wide roared through the Oklahoma City suburbs Monday, flattening entire neighborhoods, setting buildings on fire and landing a direct blow on an elementary school. (AP Photo)

A child is pulled from beneath a collapsed wall at the Plaza Towers Elementary School in following a tornado in Moore, Okla (AP Photo)

Alli Christian, left, returns Jessica Wilkinson's dog Bella to her after finding the pet amid the wreckage of Wilkinson's home shortly after a tornado struck (AP Photo)