A revived Hurricane Ian threatened coastal South Carolina and the historic city of Charleston with severe flooding Friday after the deadly storm caused catastrophic damage in Florida and trapped thousands in their homes.

With South Carolina's coast under a hurricane warning, many left Charleston for higher ground and store owners used sandbags to ward off high water levels in an area prone to inundation.

Ian left a broad swath of destruction after it came ashore Wednesday on Florida's Gulf Coast as one of the strongest storms ever to hit the U.S. The storm flooded areas on both of Florida's coasts, tore homes from their slabs, demolished beachfront businesses and left more than 2 million people without power. At least seven people were confirmed dead in the state - a number that was likely to increase as officials confirm more deaths and continue searching for people.

In Charleston on Friday, powerful wind gusts bent tree branches and sent sprays of steadily falling rain sideways. Streets in the 350-year-old city were largely empty, an ordinarily packed morning commute silenced by the advancing storm.

With winds holding at 140 kph, the National Hurricane Center's update at 8 a.m. Friday placed Ian about 175 km southeast of Charleston and forecast a 'life-threatening storm surge' and hurricane conditions along the Carolina coastal area later Friday.

The hurricane warning stretched from the Savannah River to Cape Fear, with flooding likely across the Carolinas and southwestern Virginia, the center said. The forecast predicted a storm surge of up to 2.1 meters into coastal areas of the Carolinas, and rainfall of up to 20 centimeters.

Osceola County Sheriffs use a fanboat as they urge residents to leave a flooded area following Hurricane Ian on Sept. 30, 2022 in Kissimmee, Florida.

In Florida, rescue crews piloted boats and waded through riverine streets Thursday to save thousands of people trapped amid flooded homes and buildings shattered by Hurricane Ian.

Florida Gov. Ron DeSantis said rescue crews have gone door-to-door to more than 3,000 homes in the hardest-hit areas.

'There's really been a Herculean effort,' he said Friday during a news conference in Tallahassee.

Climate change added at least 10% more rain to Hurricane Ian, according to a study prepared immediately after the storm, said its co-author, Lawrence Berkeley National Lab climate scientist Michael Wehner.

Those killed in Florida included a 67-year-old man who was waiting to be rescued and fell into rising water inside his New Smyrna Beach home late Thursday, the Volusia County Sheriff's Office said. Patrol vehicles had been unable to reach him because roads were flooded.

At least three people were reported killed in Cuba after the hurricane struck there on Tuesday.

In the Fort Myers area, businesses near the beach were completely razed, leaving twisted debris. Broken docks floated at odd angles beside damaged boats. Fires smoldered on lots where houses once stood.

An aerial view of damaged boats and property after Hurricane Ian caused widespread destruction in Fort Myers, Florida, Sept. 30, 2022.

'I don't know how anyone could have survived in there,' William Goodison said amid the wreckage of a mobile home park in Fort Myers Beach where he'd lived for 11 years. Goodison said he was alive only because he rode out the storm at his son's house inland.

The hurricane tore through the park of about 60 homes, leaving many destroyed or mangled beyond repair, including Goodison's single-wide home. Wading through waist-deep water, Goodison and his son wheeled two trash cans containing what little he could salvage - a portable air conditioner, some tools and a baseball bat.

The road into Fort Myers was littered with broken trees, boat trailers and other debris. Cars were abandoned on the road, having stalled when the storm surge flooded their engines.

Emergency crews sawed through toppled trees to reach stranded people. Many in the hardest-hit areas were unable to call for help because of electrical and cellular outages.

A chunk of the Sanibel Causeway fell into the sea, cutting off access to the barrier island where 6,300 people live.

Hours after weakening to a tropical storm while crossing the Florida peninsula, Ian regained strength Thursday evening over the Atlantic. The National Hurricane Center predicted it would hit South Carolina as a Category 1 hurricane Friday, still much weaker than the Category 4 hurricane it was on Wednesday.

National Guard troops were being positioned in South Carolina to help with the aftermath, including any water rescues. And in Washington, President Joe Biden approved an emergency declaration for the state, a needed step to speed federal assist for recovery once Ian passes.

The storm was on track to later hit North Carolina, forecasters said. Gov. Roy Cooper urged residents to prepare for torrents of rain, high winds and potential power outages.