Residents can be seen wading through deep floodwater in New Bern as they attempt to retrieve their belongings.
"We're deeply concerned for whole communities which could be wiped away".
Utility officials say almost 900,000 homes and businesses were without power in the Carolinas on Friday and more were expected to lose power.
And Hurricane Florence, though far from the fastest-windspeed storm in recent memory, remains a significant threat precisely due to the large surge and huge rainfall it's dumping on affected areas. The few cars out on a main street in Wilmington had to swerve to avoid fallen trees, metal debris and power lines.
But storms can come at any time as hurricane season lasts throughout October, Iyer said, and meteorologists can't accurately forecast where a storm will hit until about two to three days out.
A fourth person reportedly was killed while plugging in a generator in the state's Lenoir County, according to USA media.
The National Hurricane Centre said Florence 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.
In New Bern, population 29,000, flooding on the Neuse River trapped people, and Mayor Dana Outlaw told The Charlotte Observer that about 200 had been rescued by 5 a.m. Residents reached out for help through the night by phone and social media.
The National Hurricane Center downgraded it to a tropical storm on Friday, but warned that life-threatening storm surges - in which water is pushed by a storm over land that would normally be dry - catastrophic freshwater flooding were still expected.
These types of slow-moving storms - like Hurricane Harvey - can be particularly risky because of the rain and flooding they can bring.
According to poweroutage.us, more than 500,000 customers in North Carolina and 50,000 in SC were without power on Friday morning, though the Weather Channel estimates up to 3 million customers could lose power in the Carolinas due to Florence.
"Hurricanes normally come in and they go inland, which sucks the power out of them as they go over the land", he said.
"This storm is going to continue its violent grind across our state for days", Cooper said.
A fallen tree lies atop the crushed roof of a fast food restaurant after the arrival of Hurricane Florence in Wilmington, North Carolina, U.S., September 14, 2018. The NHC said parts of North and SC may get as much as 40 inches of rain.
North Carolina utilities have estimated that as many as 2.5 million state residents could be left without power, the state's Department of Public Safety said.
As it moves inland, the storm is expected to bring its high winds and intense rain bands across the southeastern corner of North Carolina and a large chunk of SC.