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

The threat of tornadoes moved east into the Mississippi Valley and Deep South on Saturday, a day after a massive storm system moving across the country unleashed winds that damaged buildings, whipped up deadly dust storms and fanned more than 100 wildfires.

Unusually vicious and damaging weather across multiple US states spawned violent tornadoes and left at least 37 people dead.

The dynamic storm from Friday through Sunday had earned an unusual “high risk” designation from weather forecasters.