Two girls stand in rubble after a tornado struck Moore, Oklahoma, May 20, 2013. A 2-mile-wide (3-km-wide) tornado tore through the Oklahoma City suburb of Moore on Monday, killing at least 51 people while destroying entire tracts of homes, piling cars atop one another, and trapping two dozen school children beneath rubble. REUTERS/Gene Blevins (UNITED STATES - Tags: ENVIRONMENT DISASTER TPX IMAGES OF THE DAY)
Two girls stand in rubble after a tornado struck Moore, Oklahoma, May 20, 2013. A 2-mile-wide (3-km-wide) tornado tore through the Oklahoma City suburb of Moore on Monday, killing at least 51 people while destroying entire tracts of homes, piling cars atop one another, and trapping two dozen school children beneath rubble. REUTERS/Gene Blevins (UNITED STATES - Tags: ENVIRONMENT DISASTER TPX IMAGES OF THE DAY)