http://www.bt.cdc.gov/disasters/tornadoes/
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Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
Knowing what to do when you see a tornado, or when you hear a tornado warning, can help protect you and your family. During a tornado, people face hazards from extremely high winds and risk being struck by flying and falling objects. After a tornado, the wreckage left behind poses additional injury risks. Although nothing can be done to prevent tornadoes, there are actions you can take for your health and safety.