A woman and her baby were killed when a tree fell on their house and at least two other storm-related deaths were reported Friday as Hurricane Florence slammed into the Carolinas, dousing the eastern US states with torrential rain and causing rivers to burst their banks.
Hundreds of people needed to be rescued after being trapped in their homes by a storm surge of up to three metres in New Bern, a town of 30,000 in North Carolina at the confluence of the Trent and Neuse rivers.
"We are expecting several more days of rain," North Carolina Governor Roy Cooper said, describing the amount of rainfall from the hurricane as a "1,000-year event."
"Into next week our rivers are going to continue to rise and there will be more significant flooding," Cooper said.
He said there had been three confirmed deaths from the storm and several others were being investigated to determine if they were storm-related.
The mother and her baby were killed in New Hanover County when a tree fell on their house, the governor said, and one person died in Lenoir County while plugging in a generator.
Local authorities reported another death, in Pender County, when downed trees prevented emergency units from reaching a woman with a medical condition.
Local media said she had suffered a heart attack.
US media said a fifth death may have occurred when a man tried to connect two extension cords in the rain.
"This storm is going to continue its violent grind across our state for days," Cooper said.
"The storm is wreaking havoc on our state." More than 680,000 customers in North Carolina were without power and 21,000 people were being housed in 157 shelters across the state.
As of 2100 GMT, maximum sustained winds had weakened to 110 kilometres per hour but the NHC warned Carolina residents to be alert for life-threatening storm surges and "catastrophic freshwater flooding."
"Flash flooding will be extreme and flood waters will come up quickly and seemingly out of nowhere," the governor said.
"We're deeply concerned for whole communities which could be wiped away." Some of the worst floodings was in New Bern, where authorities were enforcing a curfew.
Both the Trent and Neuse rivers overflowed their banks, flooding homes, stores and streets and trapping many people in their houses.
"WE ARE COMING TO GET YOU. You may need to move up to the second story, or to your attic, but WE ARE COMING TO GET YOU," the authorities in New Bern said on Twitter.
Governor Cooper said there have been "several hundred" rescue operations and "there are still some people they need to get to."
Besides federal and state emergency crews, rescuers were being helped by volunteers from the so-called "Cajun Navy" who also turned up in Houston during Hurricane Harvey to carry out water rescues.
The NHC described Florence as a "slow mover" and said it had the potential to dump historic amounts of rain on North and South Carolina, as much as one meter in some places.
"This is not the end of it," said Jeff Byard, associate administrator for response and recovery at the Federal Emergency Management Agency (FEMA).
He said "24 to 36 hours remain for significant threats" from heavy rain, storm surge and flooding.
A tornado watch was issued for eastern North Carolina.
In Wilmington, near where the eye of the hurricane touched down, trees and power lines were felled and many windows had been broken. The streets were mostly deserted and some were blocked by fallen trees.
The city awoke Friday to the sound of exploding electrical transformers with strong gusts of wind throwing street signs and other debris as well as water in all directions.
In Wilmington, Mason Tarr said he spent the night at a friend's house but didn't sleep well.
"And it's just a Category 1 hurricane," Tarr said. "I wonder how it would have been with a Category 4 or 5.
"Our house is on high ground so we're not worried about the flooding," he said. "But there are a lot of big trees around so we preferred to spend the night at friends to be sure.
"We're out of power so we spent the first few hours of the day playing board games with candles," he said.
A state of emergency was declared in five coastal states -- North Carolina, South Carolina, Georgia, Maryland and Virginia.