Residents are surveying damage from unusually vicious weather in multiple U.S. states where violent twisters, blinding dust storms and fast-moving wildfires decimated entire neighborhoods.

Eleven storm-related fatalities were reported in the Missouri counties of Ozark, Butler, Wayne and Jefferson, the state highway patrol said. Three people were confirmed dead in Independence County, Arkansas, the state's emergency management division said. Four were reported dead in Texas, officials said Saturday.

About 47 million people faced an enhanced to moderate severe storm threat from Madison, Wisconsin, to Birmingham, Alabama.

In some extreme cases, thunderstorms can spawn a derecho, a long-lived windstorm with gusts over 100 mph, strong enough to cause widespread destruction. If a severe thunderstorm warning mentions damaging winds or a derecho, take cover immediately—just as you would for a tornado.