Army National Guardsmen assist with evacuation efforts over the weekend during torrential rains from Hurricane Matthew in Fayetteville, N.C. (Staff Sgt. Jonathan Shaw/Army National Guard via AFP/Getty Images)

Hurricane Matthew has left at least 11 dead in North Carolina, Gov. Pat McCrory said Monday, pushing the death toll across the Southeast to at least 22 even as the weakening storm still carried dangers of flooding.

Five people also remained missing in Johnson and Cumberland counties, while thousands across North Carolina still lacked power after the storm struck Sunday with downpours and high winds in its slow march up the Atlantic coast, McCrory (R) told reporters.

McCrory warned that flooding remained an acute threat to people across central and eastern North Carolina.

“The people who live near rivers, streams and levees need to be extremely careful,” he warned, stressing that this would extend through much of the week.

He said that in Lumberton — a small city about 70 miles inland — about 1,500 residents were stranded by flooding, with some stuck on roofs.

Footage captured by residents along the North Carolina coast shows flooded streets and houses in the wake of Hurricane Matthew. (Erin Patrick O'Connor/The Washington Post)

“Helicopters, boats and swift water teams are going very heavily” to that area, McCrory said.

The latest confirmed victim was a 75-year-old man whose body was found in his car in an area of Gates County that was inundated by floodwaters, the state Emergency Operations Center reported. The car was discovered when the floodwaters began to recede Monday.

McCrory said the Federal Aviation Administration had issued temporary flight restrictions to keep the airspace over Lumberton clear for helicopters involved in rescue missions and pleaded with people not to send drones to the region.

“I cannot stress that more,” he said. “The drone is a whole new technology, but it can be a very dangerous technology also in this type of situation.”

Across the region, officials have also blamed Hurricane Matthew for six deaths in Florida, three in Georgia and one death each in Virginia and South Carolina. In the Caribbean, hundreds of deaths in Haiti have been attributed to the storm, and contaminated water is causing an outbreak of cholera there.

Even after the storm was downgraded to a post-tropical cyclone on Sunday and it moved out to sea, officials warned that the worst is not over. It could be days before waters crest and repair crews are able to reach all of those who have been affected, they said.

Significant flooding continues in parts of South and North Carolina, according to the National Weather Service. Up to 20 inches of rain have been reported in some areas, with more expected.

Officials in North Carolina had feared a repeat of 1999’s Hurricane Floyd, the state’s worst natural disaster, a weeks-long event that destroyed whole communities. As with Floyd, Matthew followed a prolonged period of rain in eastern and central North Carolina.

“A day and a half ago, we warned that this was going to be like Hurricane Floyd,” McCrory said. “I was afraid we were exaggerating. Now, people in eastern North Carolina are telling us we may have underestimated it.”

By Sunday, strong winds had toppled trees through much of the central region of the state, knocking out power to about 770,000 homes. In Raleigh, the dam at Lake Benson was breached. Forty-three counties declared local states of emergency, and 4,200 people were in shelters.

More than 1,700 people have been rescued in North Carolina. “We’re still rescuing people,” said Michael Martin, a battalion chief with the Fayetteville Fire Department, on Sunday. In the early hours of the storm, most of those rescued were motorists, he said, but as floodwaters rose, teams started evacuating people trapped in homes.

Local officials expect the wreckage to get worse through the next few days, following the pattern of Hurricane Floyd. A massive wall of water will flow east to the Atlantic, flooding the same towns and submerging the same low-lying communities along the creeks and rivers. It would be the second 500-year flood event in the region in two decades.

Communities along the Tar River, where Floyd’s floodwaters dealt their most serious blow, are facing the same or worse. The river is due to crest at record levels early this week in Princeton, a small, historic African American community that was almost completely submerged in 1999 and whose rebuilding was an emblem of recovery.

“Those towns and cities that are in the way of this massive water coming down are in danger as we speak,” McCrory said in a briefing Sunday afternoon.

On Sunday, the Cape Fear River at Manchester near Fayetteville stood at 31 feet, two feet above its record. By Friday, that water is expected to flood more than 200 structures in the town of Burgaw, about 75 miles downriver. Heavy flooding now in Raleigh is flowing into the Neuse River and is due in Kinston on Friday at a level one foot above the record set in 1999.

“Kinston is preparing for the worst flooding they’ve ever seen,” McCrory said.

Residents of the southeastern coast of North Carolina emerged shaken after two days of intense wind and rain.

Dave Sinclair, owner of the Ocean Grill and Tiki Bar at Carolina Beach, ventured out with his two children during a lull in the storm to survey the damage. As they watched the waves claw at the coastline, Sinclair said he told his children to respect Hurricane Matthew’s power even in its weakened state. “I told them, ‘Guys, this is barely a 1, keep this in mind,’ ” Sinclair said. “These are intensely powerful storms.”

In South Carolina, where nearly 650,000 people are without power, state and city officials are urging residents to stay away as authorities assess the damage to bridges and roadways. Communities such as Folly Beach and Sullivan’s Island remained closed to residents who had evacuated from their homes days earlier.

Nearly three feet of water threatened homes in downtown Charleston, and several streets were under about a foot of water as residents came out to start cleaning up. The flooding brought dirt, trash and debris onto the carefully manicured lawns and front porches of homes in the historic city.

While Charleston is beginning to clean up, coastal communities to its south remain under evacuation orders, state officials said.

Residents in parts of Georgetown and Horry counties have not been allowed to return home.

Several coastal roads were impassable, blocked by fallen trees and debris, local officials said. Meanwhile, sand dunes were washed away on the beach, and roofs were lifted off homes.

“It looks like the areas further south were the worst-hit. We aren’t completely sure and assessments are ongoing,” said Derrec Becker, a spokesman for the South Carolina Emergency Management Division.

The storm hugged the Florida coast, delivering a severe downpour and strong winds that downed trees for hundreds of miles and left 1.1 million people without power, but Matthew didn’t make landfall and cause the level of damage some local officials had feared. “We are blessed that Hurricane Matthew did not make landfall in Florida, but there has been significant damage across our east coast,” Florida Gov. Rick Scott (R) said in a tweet on Sunday.

Still, it reduced Florida’s scenic Atlantic Coast Highway or A1A — the economic lifeline of the state’s small beach towns — to an impassable pile of concrete and asphalt rubble. The National Guard is preventing access to the southernmost tip of Crescent Beach, where the storm chewed up A1A, leaving eight-foot holes in some places.

And in St. Augustine, the oldest city in the country, the wreckage is severe. Flagler College and City Hall, which both date to 1888, are waterlogged. Trees are down and power is out.

In the Davis Shores neighborhood of St. Augustine, some residents put the entire contents of their homes on their lawns to be thrown away because of contamination from raw sewage and water, said Mayor Nancy Shaver, who toured the area.

“But forget property and businesses,” Shaver said. “We came so close to losing many lives.”

In Georgia, the damage also was not as bad as local officials feared. Thirty counties have been declared federal disaster areas, and residents should continue to stay away from St. Simon Island. “It is considered a public health hazard due to raw sewage on the streets,” said Georgia Gov. Nathan Deal (R).

Deal, who surveyed the area between Savannah and Brunswick by helicopter, said he “ was pleasantly surprised on what I saw.”

“We have been very fortunate. I am grateful,” he said.

Ross reported from Fayetteville, N.C.; Hernández in Charleston, S.C.; Merle in St. Augustine, Fla. Sharon Dunten in Brunswick, Ga., and Mark Berman in Washington contributed to this report.