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

Millions of Americans across the country are on alert for a severe weather outbreak as violent, long-track tornadoes with damaging winds of up to 80 mph and large hail are expected across the Midwest and South with the cross-country storm moveing east.

The threat of tornadoes moved east into the Mississippi Valley and the south on Saturday, just a day after a massive storm in several central states.