Hurricane Helene kills at least 52 - as dozens rescued from Tennessee hospital roof in 'dangerous operation'

At least 52 people have been killed after Hurricane Helene barrelled its way across the southeastern US, causing billions of dollars of destruction.

Emergency crews raced to rescue people trapped in flooded homes after Helene struck the coast of Florida as a highly destructive Category 4 storm.

It generated a massive storm surge, wreaking a trail of destruction extending hundreds of miles north.

Millions are without power in Florida and neighbouring states, while some face a continued threat of floods.

Meanwhile, dozens of patients and staff have been rescued from the roof of a flooded Tennessee hospital following a "dangerous rescue operation".

Tennessee Senator Bill Hagerty said more than 50 people are now safe after becoming stranded on the Unicoi County Hospital.

The hospital was engulfed in "extremely dangerous and rapidly moving water", according to Tennessee's Ballad Health, making a boat rescue too treacherous.

A police helicopter was ultimately able to land on the roof after other helicopters failed to reach the hospital due to the storm's winds.

Local official Michael Baker told Sky News the flooding was "unprecedented".

"We've never seen anything like this," he said.

Helene struck late on Thursday night with maximum sustained winds of 140 mph (225 kph) in the rural Big Bend area, the northwestern part of Florida.

The National Hurricane Center said preliminary information shows water levels reached more than 15ft above ground in that region.

US President Joe Biden approved emergency declaration requests from the governors of several southern states affected by Helene.

Georgia, Florida, Alabama, North Carolina and South Carolina are being supported by emergency response personnel including search and rescue teams, medical support staff and engineering experts.

Georgia Governor Brian Kemp said dozens of people were trapped in buildings damaged by the storm, with multiple hospitals in southern Georgia without power.

In western North Carolina, Rutherford County emergency officials told residents near the Lake Lure Dam to immediately evacuate to higher ground, warning "Dam failure imminent".

Meanwhile, Florida Governor Ron DeSantis said the damage from Helene in the area appears to be greater than the combined damage of Idalia and Hurricane Debby in August. "It's demoralising," he said.

Many stranded in places like Tampa could only be reached by boat, with officials warning the water could contain live wires, sewage, sharp objects and other debris.

Prior to the hurricane making landfall, officials in Florida begged residents to evacuate. The sheriff's office in rural Taylor County issued a chilling warning to those who refused to leave.

"Please write your name, birthday, and important information on your arm or leg in a permanent marker so that you can be identified and family notified," the post on Facebook said.

The storm, now a post-tropical cyclone, was expected to hover over the Tennessee Valley on Saturday and Sunday, the National Hurricane Center said.

Several flood and flash flood warnings remained in effect in parts of the southern and central Appalachians, while high wind warnings also covered parts of Tennessee and Ohio.