At least 43 dead as Helene cuts through southeastern US

At least 43 people have been killed by Hurricane Helene that swamped neighborhoods, triggered mudslides, threatened dams and left more than 3.5 million homes and businesses without power, in the US on Friday.

Before moving north through Georgia and into Tennessee and the Carolinas, Helene hit Florida's Big Bend region as a powerful Category 4 hurricane on Thursday night, packing 140 mph (225 kph) winds. It left behind a chaotic landscape of overturned boats in harbours, felled trees, submerged cars and flooded streets.

By early Friday afternoon, the storm had been downgraded to a tropical depression with maximum sustained winds of 35 mph (55 kph), the National Hurricane Center said.

But Helene's heavy rains were still producing catastrophic flooding in many areas, with police and firefighters carrying out thousands of water rescues throughout the affected states.

More than 50 people were rescued from the roof of a hospital in Unicoi County, Tennessee, about 120 miles (200 km) northeast of Knoxville, state officials said, after floodwaters swamped the rural community.

Rising waters from the Nolichucky River were preventing ambulances and emergency vehicles from evacuating patients and others there, the Unicoi County Emergency Management Agency said on social media. Emergency crews in boats and helicopters were conducting rescues.

Elsewhere in Tennessee, Rob Mathis, the mayor of Cocke County, ordered the evacuation of downtown Newport because of a potential dam failure nearby. Mathis initially said the Walters dam had suffered a "catastrophic failure" but later said the dam "was breached" but there had been no major failure as yet.

The Tennessee Emergency Management Agency wrote on social media that the Walters dam, which is located just across state lines in North Carolina, had not failed. The agency said that information came from Duke Energy, which operates the dam.

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

The extent of the damage in Florida began emerging after daybreak on Friday.

In coastal Steinhatchee, Florida, a storm surge - the wall of seawater pushed ashore by winds - of eight to 10 feet (2.4-3 meters) moved mobile homes, the National Weather Service said on X. In Treasure Island, a barrier island community in Pinellas County, boats were grounded in front yards.

The city of Tampa posted on X that emergency personnel had completed 78 water rescues of residents and that many roads were impassable because of flooding. The Pasco County sheriff's office rescued more than 65 people overnight.

Officials had pleaded with residents in Helene's path to heed evacuation orders, with National Hurricane Center Director Michael Brennan describing the storm surge as "unsurvivable."