ATLANTA >> Tropical cyclone Helene brought life-threatening flooding to the Carolinas today after leaving widespread destruction as a major hurricane in Florida and Georgia overnight that killed at least 33 people, swamped neighborhoods and left more than 4 million homes and businesses without power.

Helene hit Florida’s Big Bend region as a powerful Category 4 hurricane on Thursday at 11:10 p.m. ET and left 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, including in Atlanta, where an apartment complex had to be evacuated due to flooding.

Helene came ashore in Florida with 140 mph winds, weakening to a tropical storm as it moved into Georgia early today. As of early afternoon, the storm had been downgraded to a tropical depression and was packing maximum sustained winds of 35 mph as it slowed over Tennessee and Kentucky, the National Hurricane Center said.

Helene’s heavy rains were still producing catastrophic flooding in the southern Appalachians, the NHC said.

More than 50 people were trapped on the roof of a hospital at midday today in Unicoi County, Tennessee, about 120 miles northeast of Knoxville, local media reported, as 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, but emergency crews in boats were conducting rescues.

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

In nearby Buncombe County, landslides forced interstates 40 and 26 to close, the county said on X.

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

In coastal Steinhatchee, a storm surge — the wall of seawater pushed ashore by winds — of eight to 10 feet moved mobile homes, the NWS said on X. On 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.

The U.S. Coast Guard said it had saved nine people from storm waters. Video posted online showed a Coast Guard crew pulling a man and his dog wearing life vests from the ocean on Thursday after his sailboat became disabled off Sanibel Island.

Kevin Guthrie, Florida’s emergency management director, urged residents in the affected areas to stay off the roads.

“I beg you, do not go out,” Guthrie said at a morning press briefing. “We have 1,500 search and rescue personnel in the impacted areas. Please get out of the way so we can do our jobs.”

Officials had pleaded with residents in Helene’s path to heed evacuation orders, describing the storm surge as “unsurvivable,” as NHC Director Michael Brennan warned.

In Taylor County, the Sheriff’s Department wrote on social media that residents who decided not to evacuate should write their names and dates of birth on their arms in permanent ink “so that you can be identified and family notified.”

Some residents had stubbornly stayed put.

Ken Wood, 58, a state ferry boat operator in Pinellas County, said he should have heeded evacuation orders rather than riding out the storm at home with his 16-year-old cat, Andy.

“I’ll never do that again, I swear,” Wood said. “It was a harrowing experience. It roared all night like a train. It was unnerving. The house shook.”

Down the hill from his house, the storm flooded some homes with chest-deep salt water. One house caught fire and burned down, shooting 30-foot flames in the stormy sky, he said.

“Old Andy seemed like he didn’t care,” Wood said. “He did fine. But next time we leave.”

Some of Wood’s neighbors were not as fortunate. Pinellas County Sheriff Bob Gualtieri said first responders were unable to answer several emergency calls from residents overnight due to the conditions. Today, county authorities found at least five people dead.

Two other people in Florida died, Gov. Ron DeSantis confirmed. Georgia Gov. Brian Kemp cited 11 storm-related fatalities in his state so far, while North Carolina Gov. Roy Cooper said there had been two deaths in his state.

At least 13 people had died during the storm across South Carolina, the Charleston-based Post and Courier newspaper reported, citing local officials.

Helene was unusually large for a Gulf hurricane, forecasters said, though a storm’s size is not the same as its strength, which is based on maximum sustained wind speeds.

A few hours before landfall, Helene’s tropical-storm winds extended outward 310 miles, according to the National Hurricane Center. By comparison, Idalia, another major hurricane that struck Florida’s Big Bend region last year, had tropical-storm winds extending 160 miles about eight hours before it made landfall.

Airports in Tampa, Tallahassee and St. Petersburg suspended operations on Thursday but reopened today, though extensive delays were expected.

More than 4.6 million homes and businesses were without power midday today in Florida, Georgia, the Carolinas and other states, according to the tracking website poweroutage.us.