A tornado killed at least six people in Alabama.
This was announced by Alabama's governor Kay Ivey on Twitter.
Deputy Chief of Ambulance Services Gary Weaver told AFP the accidents happened in Autauga County.
A tornado also raged in Alabama's Dallas district.
The storm caused "significant damage," said Selma Mayor James Perkins.
He called on residents to stay away from roads and downed power poles.
A state of emergency was also declared in other counties such as Chambers, Coosa, Elmore and Tallapoosa due to the storm.
The National Weather Service also issued tornado warnings for the neighboring state of Georgia.
A tornado has been sighted near Atlanta International Airport, the busiest airport in the United States by passenger numbers.
According to the US aviation authority FAA, aircraft have to remain on the ground temporarily due to severe storms.
According to website poweroutage.com, more than 100,000 homes in Alabama and Georgia were without power.
A tornado warning from the US Weather Service is in effect for the states of Alabama, Georgia and Florida until late evening local time.