Destroyed houses and toys are seen in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Volunteer Well cleans up a destroyed barber shop in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Residents begin cleanup of a destroyed fitness center in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

A destroyed car is seen in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

A resident looks at his destroyed restaurant in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

A destroyed house is seen in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

A destroyed car is seen in a neighborhood of Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

A destroyed house is seen in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Rescuers and residents clean up a destroyed neighborhood in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Piles of rubble are seen in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Residents walk through a destroyed neighborhood in Moore, Oklahoma, May 21, 2013, one day after a tornado moved through the area. A powerful tornado attacked on Monday afternoon the southern suburbs of the Oklahoma City, capital of the U.S. state of Oklahoma, killing at least 24 people, including 9 children. (Xinhua/Song Qiong)

Photo taken on May 20, 2013 shows a panoramic view of Moore, Oklahoma, the United States. Twenty-four people were killed and 237 others injured when a massive tornado blasted the southern suburbs of Oklahoma City, the capital of the U.S. state of Oklahoma, on Monday, state officials said Tuesday. (Xinhua/Marcus DiPaola)

Rescuers dig out a house after a tornado in Moore, Oklahoma, the United States, on May 20, 2013. Twenty-four people were killed and 237 others injured when a massive tornado blasted the southern suburbs of Oklahoma City, the capital of the U.S. state of Oklahoma, on Monday, state officials said Tuesday. (Xinhua/Marcus DiPaola)

Photo taken on May 20, 2013 shows a panoramic view of Moore, Oklahoma, the United States. Twenty-four people were killed and 237 others injured when a massive tornado blasted the southern suburbs of Oklahoma City, the capital of the U.S. state of Oklahoma, on Monday, state officials said Tuesday. (Xinhua/Marcus DiPaola)

A police officer surveys damage after a tornado in Moore, Oklahoma, the United States, on May 20, 2013. Twenty-four people were killed and 237 others injured when a massive tornado blasted the southern suburbs of Oklahoma City, the capital of the U.S. state of Oklahoma, on Monday, state officials said Tuesday. (Xinhua/Marcus DiPaola)