(CNN) — As Florida contends with the ruinous damage left behind by Hurricane Ian in what officials say is likely the largest natural disaster in the state’s history, residents in South Carolina are bracing for the storm’s expected landfall mid-day Friday.

Hurricane Ian re-strengthened in the Atlantic after killing at least 19 in Florida and leaving millions without power, packing sustained winds of 85 mph on its way toward the South Carolina coast as of 5 a.m. ET Friday, with landfall expected Friday afternoon between Charleston and Myrtle Beach, forecasters said.

The storm’s destructive crawl across Florida brought extraordinary flooding and storm surges, prompting the largest emergency response in the state’s history, state Fire Marshal Jimmy Patronis told CNN Thursday. Hundreds of rescues have been taking place by land, air and sea, with residents trapped in their homes or stranded on rooftops. Some homes in Fort Myers Beach have been reduced to nothing but concrete slabs, Gov. Ron DeSantis said, calling the damage in parts of the state “indescribable.”

The hurricane slammed into Florida’s southwestern coast Wednesday as a Category 4 storm, with winds that reached as high as 140 mph, inflicting vast damage to homes, vehicles and businesses. And officials are warning it will be a long road to recovery.

Here’s what to know:

Dozens of deaths reported: At least 19 storm-related deaths have been reported so far in Florida, though that number is likely to rise. A majority of those fatalities are in hard-hit Lee and Charlotte counties. President Joe Biden said Thursday that Ian could be “the deadliest hurricane in Florida’s history.”

• More than 2 million outages: Millions of Floridians who were in Ian’s path are still in the dark as of early Friday, according to PowerOutage.us. Most counties with the highest percentage of residents without power lie in the southwest, including Lee, Charlotte, DeSoto and Hardee.

• Historic flooding in some areas: Record flooding was recorded across central and northern Florida, including at least three rivers that hit all-time flood records. Officials in Orlando warned residents of dangerous flooding, which exceeded a foot in some areas. Some standing water was electrified, they said.

Hundreds of rescues and thousands of evacuations: There have been more than 700 rescues across the state so far, the governor said Thursday, and thousands of evacuees have been reported. In Lee County, a hospital system had to evacuate more than 1,000 patients after its water supply was cut off, while other widespread evacuations have been reported in prisons and nursing homes.

• Coastal islands completely isolated from mainland: Sanibel and Captiva islands in southwest Florida are completely cut off from the mainland after several parts of the critical causeway were torn away. At least two people were killed in the storm in Sanibel and the causeway may need to be completely rebuilt, local officials said. Chip Farrar, a resident of the tiny island of Matlacha, told CNN that 50 feet of road essential to reaching the mainland bridge has been washed out, and a second nearby bridge has also collapsed.

• Storm’s impacts today: A hurricane warning has been issued from the Savannah River at the Georgia-South Carolina state line to Cape Fear, North Carolina. Considerable flooding is possible from seawater and rain, especially in parts of coastal South Carolina, where storm surge up to 7 feet and 4 to 12 inches of rain could hit, forecasters say.

As Hurricane Ian moves away from Florida, governors in South Carolina, North Carolina, Georgia and Virginia have declared emergencies.

In South Carolina, Gov. Henry McMaster implored residents not to underestimate the storm’s danger and urged them to follow storm warnings closely to prepare for impact on Friday.

When all is said and done, Ian’s storm system will likely have left behind lasting changes in its wake.

The coastlines along Georgia and South Carolina may sustain significant alterations because the powerful waves and storm surges brought by Ian could inundate coastal sand dunes, according to the US Geological Survey. In addition to flooding communities behind the dunes, USGS said, the storm may push sand back and deposit it inland, which could “reduce the height of protective sand dunes, alter beach profiles and leave areas behind the dunes more vulnerable to future storms.”

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