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

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 moving east.

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

Tornadoes hit the US Midwest and Southeast overnight, killing three in Missouri and causing widespread damage. Forecasters warn of a “high risk” threat for Mississippi and Alabama as storms intensify.

At least 26 people have been killed in a monster storm sweeping across much of the U.S. People were killed in tornadoes in Missouri and in a Kansas dust storm.