Alabama saw several tornadoes Wednesday as severe storms threatened the South and Southeast into Thursday, officials said.
"We've had multiple tornadoes with damage to residences and businesses so far today," the National Weather Service in Birmingham tweeted, urging people to take warnings seriously.
No deaths appear to have been reported.
Parts of Louisiana, Mississippi and Alabama were under "high" and "moderate" risk outlooks as large hail and damaging winds were expected to move from the southern Plains to the Southeast, according to the National Weather Service's Storm Prediction Center. High-risk severe weather outlooks are rare.
"The last time this happened in March was nine years ago," said Al Roker, co-host of NBC's "TODAY" show.
Affected areas are at risk of strong, long-track tornadoes, which remain on the ground for an extended period of time.
A possible tornado in Wayne County, Mississippi, damaged several homes and downed power lines and trees, a dispatcher with the county emergency management agency said.
In Hale County, Alabama, several homes in a subdivision were damaged in Wednesday's storms, NBC affiliate WVTM of Birmingham reported. The University of Alabama in Tuscaloosa told people to seek shelter immediately because a tornado warning Wednesday afternoon. That warning passed, but UA said that a tornado watch remained until 3 a.m.
The onslaught of storms was expected to continue into the overnight, the weather service said.
Tornadoes at night are especially dangerous, because people are often sleeping and don't hear warnings. For that reason, nighttime tornadoes are 2.5 times more likely to kill than daytime tornadoes. Compounding the danger will be that the storms will be moving quickly under the cloak of darkness in a region characterized by hills and trees that can block visibility even more. Fast-approaching storms mean less time to prepare.
Meteorologists urged people make sure they have a way to get tornado warnings that can alert and wake them up if needed. That can be done by checking to make sure notification settings are turned on for mobile devices.
Alabama Gov. Kay Ivey declared a state of emergency for all 67 counties Tuesday afternoon, citing the threat of dangerous weather, the most severe of which could happen Wednesday night into early Thursday.
Ivey tweeted Wednesday that forecasts of "widespread, possibly dangerous weather conditions," remained and she urged people to be prepared.
The emergency management agency in Jefferson County, which is where Birmingham is, tweeted a warning in all capital letters: "This severe weather event is not over."
The severe storms are expected to travel from southern Virginia into parts of the South on Thursday, including Georgia and the Carolinas, the weather service said. Widespread damaging wind gusts are expected to continue, and several tornadoes are possible.