Violent tornadoes ripped through parts of the U.S., wiping out schools and toppling semitractor-trailers in several states.

Meanwhile, dust storms spurred by high winds claimed almost a dozen lives on Friday. Eight people died in a Kansas highway pileup involving at least 50 vehicles, according to the state highway patrol. Authorities said three people also were killed in car crashes during a dust storm in Amarillo, in the Texas Panhandle.

Extreme weather warnings remain in place for Florida up through Pennsylvania Sunday before massive storm moves eastward to Atlantic Ocean

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.

A powerful storm system that tore across the United States in recent days is poised to move offshore into the Atlantic Monday, but in its wake are devastated communities across multiple states that were hit with violent tornadoes,