Matthew, now a post-tropical cyclone, begins its slow exit overnight off the East Coast, but the damage isn't over.

The death toll increased from three to seven in North Carolina, Gov. Pat McCrory announced in a 9 a.m. news conference. In addition, a person who had moved to a shelter died there because of a health ailment, he said. Overall, the death toll across the Southeast from the storm is 15, according to The Associated Press.

McCrory warned that the danger was far from over because massive rains aren’t expected to peak in rivers for another day or two. Rainfall totaled 16 inches in Tar Heel, 15 in Goldsboro, 12 in Fayetteville, 9 in Raleigh and 6 in Wilmington, he said.

Already Lt. Gov. Dan Forest’s house was “completely destroyed,” McCrory said.

“This is still an extremely dangerous situation,” McCrory said. “We will not see the rivers peak possibly until Monday and Tuesday. Our models show very, very dangerous conditions as those rivers go over their edges.”

Already 887 people have been rescued from flood waters and crews are "extremely exhausted," he said. In one case, police and National Guard members searched for a nurse who went missing overnight after her shift and found her clinging to a tree above flood waters, he said.

“Can you imagine clinging to a tree overnight?" McCrory asked. “I’m sure as the daylight comes, we’re going to see people trapped.

Power is out for about 760,000 people, largely in the eastern part of the state. Many roads are closed, including four sections of Interstate 95, a major north-south artery in the state.

"We'd prefer you not go out at this time," McCrory said of state residents in storm zones.

By 8 a.m. ET Sunday, the storm center was around 60 miles east-southeast of Cape Hatteras, N.C., moving northeast at 14 mph, according to the U.S. National Hurricane Center. It had sustained winds of up to 75 mph and some higher gusts.

The storm is expected to move eastward off the North Carolina coast by Sunday afternoon, according to the forecast. It is expected to weaken throughout Sunday and into Monday.

McCrory said at a news conference Saturday that two people died in a submerged car in Bladen County, and one person died when a car hydroplaned in Sampson County. He gave no other details.

Matthew officially made landfall Saturday morning 40 miles northeast of Charleston, S.C., the first hurricane to make landfall in the state since Gaston in 2004. Charleston was spared from the worst as Matthew dropped to a Category 1, but the historic port city still faced a 6-foot storm surge, severe flooding and fallen trees downtown.

Despite warnings from government officials and meteorologists, some Charleston business owners who left their businesses returned Saturday to find themselves pleasantly surprised at the lack of damage.

“I guess we dodged a bullet for the most part,” said Kevin LePrince, owner of LePrince Fine Art, which was protected by plywood sheets. He said an interior camera didn’t show any damage.

Farther down King Street, Geemeen Kim, owner of So Good Jewelry, was sweeping up broken glass from an apartment window across the street. But he said his store had no damage.

“We were very worried last night but everything is okay,” he said.

Ashley Parham said she “stressed out all night” about the safety of her antique store but found it undamaged Saturday. “I’m going to go home and have a nice cocktail,” she said.

South Carolina Gov. Nikki Haley said Saturday that 437,000 people were without power in the state. By 3 a.m. ET Sunday, at least 203,799 outages were reported, according to the South Carolina Electric & Gas Company's outage map.

"We're not seeing as much structural damage, which is the good news of that, as much as we're seeing flooding," Haley said Saturday during a news conference.

Some communities will be allowed to return to their homes on Sunday, depending on information from local authorities, Haley said. But the first 15 miles of I-95, coming in from North Carolina, were closed due to floods, as was a section of I-95 in Ridgeland. Other parts of the state had major roads closed due to flooding, including the Beaufort and Jasper counties.

Florida Gov. Rick Scott said the federal government approved part of his request for disaster relief for debris and emergency protective measures. But he said individual assistance and permanent repairs to government buildings, roads and parks hasn’t yet been approved.

“While we are blessed that Hurricane Matthew did not make landfall in Florida, there has been significant damage all across Florida’s east coast,” Scott said. “While the state is helping our communities any way we can, I am going to continue to fight for every available resource from the federal government so our families and businesses can rebuild and get back to normal.”

Contributing: Doug Stanglin, of USA TODAY, is reporting from McLean, Va.; Tim Smith, of The Greenville News, is reporting from Charleston, S.C. Contributing: Eric Connor, reporting for The Greenville News from Savannah; Kirk Brown reporting for The Independent Mail; WFMY-TV is reporting from Greensboro, N.C.