Rescuers clear wind-torn billboards in Daoxian County, central China's Hunan Province, March 20, 2013. Three people were killed and 52 others were injured by a tornado that struck the county before dawn on Wednesday. The local meteorological observatory said the wind speed of the tornado reached 30.7 meters per second, a record for the observatory. (Xinhua/Guo Guoquan)

 Rescuers clear wind-torn billboards in Daoxian County, central China's Hunan Province, March 20, 2013. Three people were killed and 52 others were injured by a tornado that struck the county before dawn on Wednesday. The local meteorological observatory said the wind speed of the tornado reached 30.7 meters per second, a record for the observatory. (Xinhua/Guo Guoquan)

A collapsed shed is seen in Daoxian County, central China's Hunan Province, March 20, 2013. Three people were killed and 52 others were injured by a tornado that struck the county before dawn on Wednesday. The local meteorological observatory said the wind speed of the tornado reached 30.7 meters per second, a record for the observatory. (Xinhua/Guo Guoquan)

Locals salvage articles near a collapsed shed in Daoxian County, central China's Hunan Province, March 20, 2013. Three people were killed and 52 others were injured by a tornado that struck the county before dawn on Wednesday. The local meteorological observatory said the wind speed of the tornado reached 30.7 meters per second, a record for the observatory. (Xinhua/Guo Guoquan)