The floodwaters are expected to push many rivers to all-time highs and, toward the mountains of western North Carolina and southwestern Virginia, could spur life-threatening landslides. A woman died in SC when her auto hit a fallen tree.
On Sunday, Florence claimed a 14th victim, a man who drowned when a pickup truck flipped into a drainage ditch in SC, and a 15th, after a pickup truck veered off a road and struck an overpass support beam in SC.
Cooper, however, said the storm, which was downgraded to a tropical depression early Sunday, prevented officials from seeing the full scope of the damage.
On a flooded road near New Bern, Bryan Moore and his nephew Logan chose to go swimming in the floodwaters after having spent days at home without electricity or running water. Some other parts of SC will be left with 15 inches of rain.
In Wilmington, the state's eighth-largest city, residents waited for hours outside stores and restaurants for basic necessities like water.
But the storm was shaping up as a two-part disaster, with the second, delayed-action stage consisting of inland flooding, caused by rainwater working its way into rivers and streams. Mandatory evacuations were issued for South Lumberton on Saturday.More news: Musk signs up first passenger for round-the-moon trip on SpaceX
Florence also now stands as the sixth-highest tropical cyclone rainfall total across the US for records dating back to 1950.
"It has already dumped 50 to 76 cm of rain on parts of the Carolinas with more to come", he said.
In addition to the physical damage being done by Florence - it has already left tens of thousands of homes damaged - experts warn of psychological disruption for residents along its path. Sarah Thompson, who is helping lead Save the Children's response to Florence, told NPR children are among the most vulnerable to emotional trauma from a major storm. "Nothing I ever experienced before, I was truly scared", he told AFP. About 500,000 homes and businesses were in the dark.
The rain was unrelenting in Cheraw, a town of about 6,000 people in northeastern SC.
North Carolina is confronting a spiralling crisis as tropical depression Florence slowly ravages the region, flooding cities, endangering communities from the coastline to the rugged mountains, and requiring many more than 1000 rescues. Disaster experts say it's often hard to quickly confirm hurricane-related fatalities because of the vast regions storms can affect. More than 26,000 were in shelters. It was moving west at 8 miles per hour, whipping 35 miles per hour winds. Add Hurricane Florence as an interest to stay up to date on the latest Hurricane Florence news, video, and analysis from ABC News.
Gaston County manager Earl Mathers said in an email to commissioners the tree fell on a mobile home Sunday in Dallas, about 240 miles west of where Hurricane Florence made landfall Friday in Wrightsville Beach.
Tornadoes remain a threat, with the NHC saying that "a few tornadoes are possible in southeastern North Carolina and northeastern SC". More than 900 water rescues have been reported in North Carolina alone, the governor's office said - but many more people need help. So it's "time to go out and have a drink".