Flash-flooding in Kentucky has left eight dead and entire towns submerged beneath the water.
People were forced to clamber onto roofs to avoid the fast-rising water after torrential rainfall caused rivers to burst their banks.
Homes and businesses were inundated across the Appalachia region in the east of the state and there are fears many are still trapped.
Rescue workers are battling to reach communities entirely cut off by the extreme weather and have warned the public the death toll could rise.
Flooding and landslides hit a rural part of the state where many live in small communities perched on hillsides and in remote areas.
Helicopters and boat crews were drafted in to rescue people from stricken towns and villages across eastern Kentucky and into Virginia.
With roads to remote settlements cut off, trapped families may have to wait for the water to recede before help can reach them.
Kentucky governor Andy Beshear said: ‘In a word, this event is devastating
‘And I do believe it will end up being one of the most significant, deadly floods that we have had in Kentucky in at least a very long time.’
He continued: ‘There are a lot of people in eastern Kentucky on top of roofs waiting to be rescued.
‘There are a number of people that are unaccounted for and I’m nearly certain this is a situation where we are going to lose some of them.’
Continued rainfall and dangerous conditions have hampered search and rescue operations, the state said.
The governor urged Kentuckians to offer help and make donations where possible, adding: ‘We’ve got a lot of people that need help that we can’t get to at the moment. We will.’
Forecasters have warned similar scenes could be repeated in neighbouring Virginia, West Virginia and some parts of Kentucky as rainstorms are set to continue.
According to online data, at least 30,000 people are still without power.
Jerry Stacy, a rescue worker on the ground, described the flood as a ‘catastrophic event’.
He said: ‘We’re just in the rescue mode right now. Extreme flash flooding and mudslides are just everywhere.’
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