Florence's five fatalities included a mother and her infant killed after a tree fell on their house in Wilmington, the city's police department said.
He said residents should "expect flooding and potential landslides tonight and into Monday", and warned against driving in the water "no matter how confident you feel or how much you want to get out of the house".
By 2 p.m. Saturday, the storm won't even be halfway across SC, forecasters say.
Florence came ashore more than 24 hours ago.
Hurricane Florence, weakened but still risky, has crashed into the Carolinas on Friday as a giant, slow-moving storm that stranded residents with floodwaters and swamped part of the town of New Bern at the beginning of what could be a days-long deluge.
It diminished from hurricane force as it came ashore, but forecasters said the 350-mile-wide storm's slow progress across North and SC could leave much of the region under water in the coming days.
WILMINGTON: Florence barreled into the Carolina coast and moved inland on Friday, knocking down trees, overflowing rivers, dumping sheets of rain and leading to the death of five people before it was downgraded to a tropical storm still capable of wreaking havoc.
The storm battered the coastline throughout Friday and Saturday with hurricane-force winds and as much as 2ft (60cm) of rain in some areas of North Carolina. New Bern Mayor Dana Outlaw told The Charlotte Observer about 200 people already had been rescued by 5 a.m.
The evacuation order for the Lowcountry is lifted as Tropical Storm Florence moves out of the coast areas and into the Midlands.
Roads became flooded, trees blown over and homes destroyed as some parts of North Carolina have already seen surges of flood water as high as 10ft.
Hurricane Florence is continuing on its deadly path, causing widespread flooding and damage despite its downgrading to a tropical storm.
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Officials in New Bern, which dates to the early 18th century, said more than 100 people were rescued from floods and the downtown was under water by Friday afternoon.
Authorities warned, too, of the threat of mudslides and the risk of an environmental disaster from floodwaters washing over industrial waste sites and hog farms.
Two fins were spotted in the high water in Wilmington.
The death toll is likely to rise.
The hurricane center said the storm will eventually break up over the southern Appalachians and make a right hook to the northeast, its rainy remnants moving into the mid-Atlantic states and New England by the middle of next week. That's enough to fill the Chesapeake Bay, or cover the entire state of Texas with almost 4 inches of water.
Florence is forecast to "drop nearly double" the volume of rain over the state compared to Floyd, tweeted Ryan Maue, meteorologist for weathermodels.com.
In Jacksonville, North Carolina, next to Camp Lejeune, firefighters and police fought wind and rain as they went door-to-door to pull dozens of people out of the Triangle Motor Inn after the structure began to crumble and the roof started to collapse.
Parts of North and SC were forecast to get as much as 40 inches of rain (1 meter).
"WE ARE COMING TO GET YOU", the city of New Bern tweeted around 2 a.m.
"WE ARE COMING TO GET YOU", New Bern city officials said on Twitter. Many of them are boat owners, who help rescue stricken flood victims. Water rescues were also underway, although it was hard to know how many had occurred. "We got thrown into mailboxes, houses, trees", said Holt, who had stayed at home because of a doctor's appointment that was later cancelled.
Ashley Warren and boyfriend Chris Smith managed to paddle away from their home in a boat with their two dogs and were left her shaken. Local media said she suffered a heart attack.