More than a quarter of a million homes and businesses were without power and North Carolinians were told to shelter in place as Hurricane Dorian, still a powerful Category 1 storm, drenched the coasts of the Carolinas and began spreading hurricane conditions along parts of the North Carolina coast early Friday.

More than 275,000 customers were without power, most of them in counties along the South Carolina coast and immediately inland, and many roads were closed by flooding.

Full coverage: Latest stories and video on Hurricane Dorian

"It has only started. We have a long night ahead of us," Gov. Roy Cooper said in urging North Carolinians to shelter in place on Thursday.

"Get to safety and stay there," Cooper said. "This won't be a brush-by. Whether it comes ashore or not, the eye of the storm will be close enough to cause extensive damage in North Carolina."

The Latest on Dorian:

At 1 a.m., the hurricane was about 40 miles east-northeast of Wilmington, North Carolina, and was moving northeast at about 15 mph.

The storm had weakened to a Category 1 storm with maximum sustained winds of about 90 mph.

Forecasters said the center of Dorian was expected to move near or make landfall over the North Carolina coast overnight or Friday.

At least 30 people have died in the Bahamas, according to the health minister, and more deaths are expected to be reported.

A second storm-related death was confirmed in North Carolina after a man died while moving his boat at an Inner Banks marina, authorities said.

The core of Dorian was brushing the coast at 1 a.m. as a Category 1 storm, with maximum sustained winds of 90 mph. Tropical storm-force winds extended hundreds of miles from the eye, which was about 35 miles east-northeast of Wilmington, North Carolina.

The storm was moving northeast at about 15 mph, and it was possible that it could make landfall over the North Carolina coast later Friday.

Flash floods were reported along the coasts of both Carolinas, the National Hurricane Center reported. It said "significant, life-threatening flash flooding" was expected as far north as southeast Virginia through the night.

Officials in Georgetown County, South Carolina, suspended all emergency services until winds subside enough to ensure safety, NBC affiliate WMBF of Myrtle Beach reported. People calling 911 were being added to a list to be responded to later, authorities said.

Most of Horry County, South Carolina's fifth-biggest county, imposed curfews through 7 a.m. Friday.

A live electric wire was knocked down in Charleston, South Carolina, igniting sparks and explosions that could be heard blocks away, WMBF reported. Charleston police urged people to take shelter as conditions worsened, even as images of people kayaking down the flooded streets of Charleston were being shared on social media.

Sara Hughes of North Charleston said she and her family were sleeping downstairs when a tree crashed into her son's upstairs bedroom on Thursday morning.

"I'm just thankful that he listens, and we all hunkered down downstairs," she told NBC affiliate WIS of Columbia.

Forecasters said Dorian would produce especially heavy rainfall across eastern North Carolina, where up to 12 inches were expected, with up to 15 inches in isolated areas.

Rain, storm surge and strong winds weren't the only threats. The National Weather Service confirmed that a tornado ripped across Emerald Isle on Bogue's Bank Island off North Carolina at 9:06 a.m. Police told NBC affiliate WITN of Washington that an RV park was heavily damaged as the tornado raced across the island and continued onto the mainland.

WITN quoted a witness as saying about half of the 50 mobile homes in the park were damaged.

A second storm-related death was confirmed in North Carolina on Thursday night.

Chris Murray, the director of emergency management in Pamlico County, told NBC News that a man died after he "suffered a medical emergency" as he was moving his boat at a marina on Wednesday. Murray said the death was considered to be related to Dorian because "otherwise, they wouldn't have been out there."

WITN quoted Sheriff Chris Davis as saying the man had a heart attack while he was moving his boat in the Inner Banks town of Oriental, about 20 miles southeast of New Bern.

An 85-year-old man from Columbus County died Monday when he fell off a ladder while preparing his house for the storm, state medical examiners said.

The American Red Cross said it was in "dire need" of blood donations as conditions had forced as many as 50 blood drives to be canceled across Georgia and the Carolinas.

"We've lost approximately 1,100 units of blood and platelet products due to the hurricane," Chris Newman, the Red Cross' district manager for donor recruitment in Asheville, North Carolina, told NBC affiliate WXII of Winston-Salem.

"Those units are things we're counting on to help meet our patient demands and their needs in the hospitals," Newman said.

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Forecasters said Dorian would continue hugging the Atlantic coast, arriving near extreme southeastern New England on Friday night and Saturday morning.

The hurricane center said it was predicted to approach the Canadian province of Nova Scotia later Saturday or Saturday night as a post-tropical cyclone — still at hurricane force. The Canadian Hurricane Center said hurricane watches for Nova Scotia would be issued Friday.

Dorian had already caused utter destruction in the Bahamas, ripping roofs and walls off homes, toppling trees, flooding streets and burying communities in debris. At least 30 people were killed, Health Minister Duane Sands told NBC News on Thursday night, adding that he believed "the number will rise dramatically."

The destruction seen in the Bahamas mirrors the damage inflicted on Puerto Rico and Dominica during hurricanes Maria and Irma in 2017, the World Meteorological Organization said in a statement.

At its peak, Dorian reached maximum sustained winds of 185 mph and caused storm surges of 18 to 23 feet.

Storm surges are a growing threat to low-lying coastal communities because of rising sea levels resulting from climate change, the meteorological organization said. Rainfall associated with tropical cyclones is also projected to increase with global warming.

Dorian has been one of the slowest-moving cyclones ever recorded. A recent study by federal scientists at NASA and the National Oceanic and Atmospheric Administration found that such stalling by storms has increased in frequency among North Atlantic hurricanes, which results in more extreme rainfall.