Authorities across south-eastern United States are facing the daunting task of cleaning up from Hurricane Helene, one of the most powerful and perhaps costliest storms to hit the country, as the death toll continued to rise.

At least 47 deaths were reported by early on Saturday (local time), and officials feared still more bodies would be discovered across several states.

Damage estimates across the storm’s rampage range between $US95 billion and $US110 billion ($NZ149 billion and $NZ173 billion), potentially making this one of the most expensive storms in modern US history, said Jonathan Porter, chief meteorologist of AccuWeather, a commercial forecasting company.

Downgraded late on Friday to a post-tropical cyclone, the remnants of Helene continued to produce heavy rains across several states, sparking massive flooding that threatened to cause dam failures that could inundate entire towns.

“The devastation we’re witnessing in Hurricane Helene’s wake has been overwhelming,” President Joe Biden said on Saturday. “Jill and I continue to pray for all of those who have lost loved ones and for everyone impacted by this storm.”

Biden was briefed about the loss of life and storm’s impact on multiple states by Deanne Criswell, administrator of the Federal Emergency Management Agency, and Liz Sherwood-Randall, the White House’s homeland security adviser, the White House said.

The president directed them to continue to focus on speeding up support to storm survivors and accelerating recovery efforts, including the immediate deployment of additional search and rescue teams into North Carolina, it added.

At least 3 million customers remained without power on Saturday afternoon across five states, with authorities warning it could be several days before services were fully restored. The worst outages were in South Carolina with more than 1 million homes and businesses without power, and Georgia where 750,000 were without power.

Some of the worst rains hit western North Carolina, which saw 76cm fall on Mount Mitchell in Yancey County, the National Weather Service’s Weather Prediction Center reported.

Atlanta was hit with 33cm of rain, and farmers in South Georgia were assessing the damage to the state’s $US1 billion cotton crop and $US400 million pecan crop now in harvest season.

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 225km/h winds. It left behind a chaotic landscape of overturned boats in harbors, felled trees, submerged cars and flooded streets.

Police and firefighters carried out thousands of water rescues throughout the affected states on Friday.

More than 50 people were rescued from the roof of a hospital in Unicoi County, Tennessee, 193km northeast of Knoxville, state officials said, after flood waters swamped the rural community.