Flood warnings remain in effect, particularly in Kentucky, Tennessee, and Alabama, according to forecasters.

Tennessee has been the hardest hit, with 10 deaths recorded in the western part of the state.

Kentucky and Missouri each report two deaths, while Arkansas, Indiana, and Mississippi each count one, with tolls that could still rise.

In Jeffersontown, Kentucky, buildings were left destroyed by a reported tornado, an AFP correspondent saw.

Photos shared on social and local media showed widespread damage from the storm across several states, with homes torn apart, toppled trees, downed power lines and overturned cars.

The National Weather Service said Sunday that "there is still some threat for heavy rainfall and flash flooding for portions of the Southeast and the Gulf Coast region going through this evening and overnight."

"Flooding has reached record levels in many communities," Kentucky's Governor Andy Beshear wrote on social media Saturday, urging residents in the state to "avoid travel, and never drive through water."

Almost 140,000 customers were without power in five affected states Sunday, according to tracking website PowerOutage.us.

Scientists say global warming is disrupting climate patterns and the water cycle, making extreme weather more frequent and ferocious.

Last year set a record for high temperatures in the United States, with the country also pummeled by a barrage of tornadoes and destructive hurricanes.