By Brad Brooks and Joseph Ax

FORT MYERS, Fla., Sept 30 (Reuters) - A resurgent Hurricane Ian barreled north on Friday toward a second landfall in South Carolina, a day after carving a path of destruction across central Florida that left rescue crews racing to reach trapped residents along the state's Gulf Coast.

Ian, which had weakened to a tropical storm during its march across Florida, regained Category 1 hurricane strength on Thursday afternoon while churning toward South Carolina above the Atlantic Ocean, with maximum sustained wind speeds of 75 mph (120 kph), the U.S. National Hurricane Center (NHC) said.

The hurricane was forecast to hit near low-lying Charleston, South Carolina, about 2 p.m. ET (1800 GMT) on Friday, bringing potentially life-threatening flooding, storm surges and winds. Hundreds of miles of coastline, stretching from Georgia to North Carolina, was under a hurricane warning.

The extent of the damage in Florida, where Ian first came ashore on Wednesday as one of the most powerful storms ever to hit the U.S. mainland, became more apparent on Thursday as emergency crews began reaching stranded residents, though the death toll remained uncertain.

NBC News reported at least 10 people had died, while CNN put the toll at 17 as of Thursday evening.

At an evening news briefing, Governor Ron DeSantis acknowledged some people had perished but declined to confirm a specific figure, warning that official confirmation was still needed.

"We fully expect to have mortality from this hurricane," he said.

Some of the damage to coastal towns, including Fort Myers Beach, was "indescribable," added DeSantis, who surveyed the affected areas from the air on Thursday.

Earlier on Thursday, President Joe Biden warned Ian could prove to be the deadliest hurricane in Florida history, saying preliminary reports suggested a "substantial" loss of life.

More than 2.3 million homes and businesses remained without power on Thursday evening, according to the tracking website PowerOutage.us.

Officials in Georgia, South Carolina and North Carolina urged residents to prepare for dangerous conditions.

Charleston is particularly at risk; a city-commissioned report released in November 2020 found about 90% of all residential properties were vulnerable to storm surge flooding. Parts of northeast South Carolina, near Charleston, could also experience up to 8 inches of rain.

Predicted storm surges were not as severe as those issued by the NHC when the storm was approaching Florida. Edisto Beach, South Carolina, a resort destination about 30 miles south of Charleston, was expected to see a 4- to 7-foot surge.