At least 21 people have died after tornadoes hit two US states, according to local officials.
Fourteen people have died in Kentucky, its governor Andy Beshear said, while seven have died in Missouri.
The weather system also saw tornadoes tear through Wisconsin, leaving hundreds of thousands of people without power.
In the city of St Louis, five people were confirmed dead and more than 5,000 homes were damaged, mayor Cara Spencer said on Saturday.
The storm system originally hit Scott County, 130 miles south of St Louis, on Friday, killing two people, Sheriff Derick Wheetley said.
The devastation that ensued saw roofs torn off buildings, blown-out windows, toppled trees, and power lines.
St Louis mayor Cara Spencer said: "Our city is grieving tonight. The loss of life and the destruction is truly, truly horrendous."
Dozens of people are believed to have been injured and in hospital, but the exact numbers in Missouri have not been confirmed.
Kentucky officials described the situation there as a "mass casualty event" after the weather system tore across Laurel County late on Friday.
Several people were taken to hospital, buildings were damaged, and a car flipped over on a busy highway, local officials reported.
Laurel County Sheriff's Office spokesman Gilbert Acciardo said rescuers had "been on the ground all night looking for possible survivors".
Kentucky governor Mr Beshear wrote on X that the number of dead in the state was likely to increase from 14 "as we receive more information".
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Further devastation expected in other states
The National Weather Service warned of further devastation hitting Texas, Kansas, and Oklahoma on Saturday.
"Severe thunderstorms producing large to very large hail, damaging gusts, and a couple of tornadoes are expected across the southern Plains," it said on its website.
The Midwest tornadoes were also expected to hit Illinois, eventually stretching to New Jersey and the Atlantic coast.
(c) Sky News 2025: 'Mass casualty event' declared as tornadoes hit Kentucky and Missouri
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