More than 20 people have died after severe storms swept through the US states of Missouri and Kentucky, laying waste to local communities and cutting off electricity to nearly 200,000 people, authorities said.

Kentucky governor Andy Beshear said on X that at least 14 people had died in the storms on Friday night, and another seven were dead in Missouri, according to local officials.

"Kentucky, we're starting today with the tough news that we lost at least 14 of our people to last night's storms, but sadly, this number is expected to grow as we receive more information," Beshear said on Saturday. "Please pray for all of our affected families."

Drone footage published by local media showed scenes of devastation in the town of London, Kentucky, with houses levelled and reduced to splinters, and tree trunks standing bare, completely shorn of branches.

Beshear added that more than 100,000 people have been left without power in the state, and five counties have declared a state of emergency.

Eastern Kentucky, an area historically known for its coal mines, is one of the poorest regions in the country.

In Missouri, five people were killed in the large city of St Louis and two in Scott County, the Missouri State Highway Patrol said in a statement.

More than 80,000 people were left without power, and three shelters were set up in the area, the statement added. More severe weather was forecast for Missouri on Sunday night and on Monday.

"Our city is grieving tonight," St. Louis mayor Cara Spencer told reporters on Friday night. "The loss of life and the destruction is truly horrendous." (AFP)