Tornadoes swept through parts of Oklahoma and Texas, killing at least one person and injuring dozens.
Search and rescue teams have been dispatched to the worst-hit areas, with people trapped in destroyed buildings.
The storm also caused flash flooding in some areas.
The two towns that bore the brunt of the tornado were Podley, Texas, and Idabel, Oklahoma, both close to the state border.
Authorities confirmed one death in Idabel, Oklahoma’s McCurtin County, in the southeastern corner of the state.
The town saw a church, medical center and school dismantled.
“The south and east sides of Idabel were completely destroyed,” said Steven Carter, emergency management coordinator for McCurtin County.
Emergency crews equipped with generators have been dispatched to the area to find missing residents.
“Prayers for Oklahomaans impacted by today’s tornadoes,” Governor Kevin Steit tweeted.
At least three other counties were also hit by storms that triggered flooding, said Klei Cain of the state’s Office of Emergency Management.
Tornadoes were also reported in Texas and Arkansas, and the storm system was moving toward Louisiana, the National Weather Service said.
In Texas, authorities in Lamar County said at least 50 homes were destroyed and 10 people were treated at a hospital, including two with serious injuries.
No deaths have been reported so far.
County official Judge Brandon Bell declared a disaster in the area, paving the way for federal aid and funding.
He said at least two dozen people were injured across the county.
After making landfall, the tornado moved north through the communities of Hopewell, Cavenes, Beaver Creek and Podley, the county sheriff’s office said.
Powderly Volunteer Fire Department chief Randy Johnson said: “It will take a long time to clean this up, but the community is coming together.
“It was really heartbreaking to see.”
The town is about 45 miles west of Idabel and about 119 miles northeast of Dallas.
Meanwhile, at least five tornadoes have been confirmed along the Mississippi and Alabama coastlines.