The deadliest tornado in recorded U.S. history occurred 100 years ago. The Tri-State Tornado touched down in southeastern Missouri on March 18, 1925.

A deadly tornado outbreak ripped through Missouri, Illinois, Arkansas and Mississippi overnight Friday, leaving destruction, power outages and tragic loss in its wake.

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.

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.

After deadly storms scourged the Heartland, volunteers are gathering from across the area to help with relief and recovery efforts.

Meanwhile, the severe weather threat will linger through Sunday from Florida northward into the upper Ohio River Valley, forecasters warned.