In Leland, a low-lying city north of Wilmington, homes and local businesses were engulfed by water.
Mayor Dana Outlaw told NBC's "Meet the Press" on Sunday that numerous creeks in the area are "increasing by the hour" and there's concern about trees falling due to the saturated ground conditions.
Rescue crews used boats to carry more than 360 people from rising water in the river town of New Bern, North Carolina, while many of their neighbours awaited help.
"The storm is picking up speed to the west", Ellis said.
"Those rivers in North Carolina that have received heavy rainfall are coming our way", Governor Henry McMaster said during a news conference.
-A 61-year-old woman was killed late Friday when the vehicle she was driving struck a tree near the town of Union, South Carolina, Capt. Kelley Hughes of the South Carolina Highway Patrol said.
Deadly storm Florence drenched North Carolina with yet more downpours on Sunday, cutting off the city of Wilmington, damaging tens of thousands of homes and threatening worse flooding as rivers fill to bursting point. "More than likely it's maybe a mindset of 'we've been through this before, '" he said.
The mayor of a Fayetteville, North Carolina, suburb says about 100 people in her community have been urged to evacuate to higher ground over flooding concerns.
Hundreds of residents were rescued on Friday, and the city was placed under a 24-hour curfew until further notice.
"There's mud all over the floor and the wood floors have buckled", she said, adding they planned to return to her brother's house because of the musty smell that pervades their home.
Florence slammed into the North Carolina coast as a large hurricane Friday, dumping almost three feet (1 meter) of rain and swelling the region's rivers.
The number of service members deployed include 7,500 from the US Coast Guard and 6,500 from the National Guard, the Federal Emergency Management Agency said.More news: Tired Boy Donald Trump Says Obama’s Speech Put Him to Sleep
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"Amazing. They did awesome", said Knox, who was stranded with seven others, including a boy who was carried out in a life vest. Heavy rain is also in the forecast, with estimates showing over 20 inches near Jacksonville and toward New Bern.
The National Weather Service warned of a "catastrophic, life-threatening flash flooding risk" in much of North Carolina, northern SC and southwest Virginia on Sunday.
The death toll rose to at least 14 from Florence, which crashed into the state as a hurricane on Friday, bringing record rainfall.
Pfaff said Eastern North Carolina residents can expect flash flooding over the course of the day Saturday.
All roadways in the state are at varying degrees of risk for flash flooding through Sunday, with major river flooding anticipated into early next week.
People clapped and shouted, "Amen!" and "Thank you, Lord".
One of those was the Waccamaw River in South Carolina's Horry County, which had reached 8.9 feet by Saturday; it floods at 11 feet.
At 2 a.m. Sunday, Florence was about 25 miles (45 kilometers) southeast of Columbia, South Carolina.
News reported 455 people were rescued by the operation.
North Carolina is bracing for what could be the next stage of the still-unfolding disaster: widespread, catastrophic river flooding from Florence. National Hurricane Center meteorologist Joel Cline said the mountains will wring water out of the moist tropical air: "It's like running into a wall, and that moisture has to go somewhere, and it goes up, creates rain, and you have torrential rain in that area".