At the height of the flooding, some residents were trapped in attics, and others couldn't escape because roads were rendered impassable by rising waters, including from the Neuse River.
Florence made landfall on Friday as a Category 1 hurricane but has since been downgraded to a tropical storm, even as it continued to wreak havoc along the East Coast, downing trees and power lines and forcing 20,000 people to flee to shelters.
Heavy rain is expected to continue in North and SC over the next few days. Another person was arrested for allegedly looting an Exxon gas station and convenience store.
President Donald Trump issued a disaster declaration for North Carolina, the White House said Saturday.
Florence was drifting westward over SC, reaching about 30 kilometres southeast of Columbia S.C., at 5 a.m. Sunday, the NHC said. The previous record of 24.06 inches was set during Hurricane Floyd in 1999.
The dead included a mother and baby killed when a tree fell on a house in Wilmington, N.C. SC recorded its first death from the storm, with officials saying a 61-year-old woman was killed when her vehicle hit a tree that fell across a highway. She tried to row out of her neighborhood Thursday night with a boat that was in her yard after her home began to flood, but had to retreat because of the poor conditions.
Two more people were killed in Lenoir County. One was killed while checking on his dogs outside while another one was electrocuted while trying to connect two extension cords, emergency officials said.
Authorities ordered the immediate evacuation of up to 7,500 people living within a mile of a stretch of the Cape Fear River and the Little River, about 100 miles from the coast.
Authorities in SC reported one death, saying a woman was killed when her vehicle struck a fallen tree. A man and woman died in Horry County due to carbon monoxide poisoning, according to SC officials.
The National Hurricane Center says excessive amounts of rain are still being dumped in North Carolina and the effect is expected to be "catastrophic". Large sections of the population are without power already in North Carolina, and would take time. Dozens of electric fix trucks massed to respond to damage expected to hit central North Carolina as rainwater collected into rivers headed to the coast.
Three more people died in Duplin County, NC, due to flash flooding, according to a post on the sheriff department's Facebook page. During Matthew, it reached 58 feet.
"The worst of the storm is behind us", she said.
"There are no roads. that are leading into Wilmington that are passable because of the flooding that is taking place now inland", Saffo said. There have been "hundreds of rescues".
At one point Sunday afternoon, part of a makeshift barrier meant to plug a low point in the city's main levee system gave way and river water leaked through - prompting workers to try to shore it back up with construction equipment.
Official predict that when the water reaches 26 feet, the barriers will be overwhelmed. An investigation is underway, but officials said it appears there's no reason for others at the shelter to worry.
But with radar showing parts of the storm over six Southeastern states and flood worries spreading into southern Virginia and West Virginia, North and SC were still in the bull's-eye.
According to the US National Hurricane Center, the storm is located 45 km northeast of the US city of Columbia (South Carolina) and continues to move deeper into the continent at a speed of around 2.5 m/s.
It is feared that more communities could become deluged as the storm crawls west at only 2mph (3km/h).