Three more people have died in North Carolina as a result of the hurricane-turned-tropical storm Florence, bringing the overall death toll to 11.
US President Donald Trump was briefed by telephone on Saturday on Florence's impact on the East Coast.
The US Marines, the Coast Guard, civilian crews and volunteers used helicopters, boats and heavy-duty vehicles to rescue scores of people trapped by Florence's shoreline onslaught, even as North Carolina braced for what could be the next stage of the disaster: widespread, catastrophic flooding inland.
A day after blowing ashore with 145km/h winds, Florence practically parked itself over land all day long and poured on the rain. With rivers rising toward record levels, thousands of people were ordered evacuated for fear the next few days could bring the most destructive round of flooding in North Carolina history.
Nearly a metre of rain had fallen in places, and the drenching went on and on.
'I cannot overstate it: Floodwaters are rising, and if you aren't watching for them you are risking your life,' Governor Roy Cooper said.
As of 5pm, Florence was centered about 95km west of Myrtle Beach, South Carolina, inching west at 4km/h - not even as fast as a person walking. Its winds were down to 75km/h. With half of the storm still out over the Atlantic, Florence continued to collect warm ocean water and dump it on land.
In its initial onslaught along the coast, Florence buckled buildings, deluged entire communities and knocked out power to more than 900,000 homes and businesses. But the storm was shaping up as a two-part disaster, with the second, delayed stage triggered by rainwater working its way into rivers and streams.
The flash flooding could devastate communities and endanger dams, roads and bridge.
Authorities ordered the immediate evacuation of up to 7500 people living within a mile of a stretch of the Cape Fear River and the Little River, about 100 miles in from the coast. The evacuation zone included part of the city of Fayetteville, population 200,000.
Officials in nearby Harnett County urged residents of about 1100 homes to clear out because the Lower Little River was rising toward record levels.
One potential road out was blocked as flooding forced the shutdown of a 26km stretch of Interstate 95, the main highway along the Eastern Seaboard.
Coast Guard helicopters were taking off across the street to rescue stranded people from rooftops and swamped cars. Coast Guard members said that choppers had made about 50 rescues in and around New Bern and Jacksonville as of noon.
The dead included a mother and baby killed when a tree fell on a house in Wilmington, North Carolina. South Carolina recorded its first death from the storm, with officials saying a 61-year-old woman was killed when her car hit a tree that had fallen across a highway. Three died in one inland county, Duplin, because of water on roads and flash floods, the sheriff's office said.
The National Hurricane Center said Florence broke a North Carolina rainfall record that had stood for almost 20 years.
Forecasters said the storm will eventually break up over the southern Appalachians and make a sharp rightward swing to the northeast, its rainy remnants moving into the mid-Atlantic states and New England by the middle of the week.