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.
Unsafe storm surges and rising tides have caused coastal areas to be flooded, with water rushing inland from the shoreline.
Myrtle Beach, South Carolina, has been lashed by torrential rains and near-hurricane force winds, CBS News correspondent Don Dahler reported.
After reaching a terrifying Category 4 peak of 225 km/h earlier in the week, Florence made landfall as a Category 1 hurricane at 7:15 a.m.at Wrightsville Beach, a few kilometres east of Wilmington and not far from the SC line.
A mother and her eight-month-old baby were killed Friday when a tree fell on a house, according to a tweet from police in Wilmington, N.C. The father was transported to a hospital for treatment.More news: Israel dismantles protest shacks near West Bank village marked for demolition
Rivers and creeks rose toward record levels, threatening flash flooding that could devastate communities and endanger dams, roads and bridges.
That kind of scenario is likely to repeat itself all over communities in Eastern North Carolina, as swollen rivers flood towns and the pouring rain adds to the misery.
U.S. media later said a man in Lenoir County died after heavy winds knocked him down as he tried to check on his dogs. It blew ashore along a mostly boarded-up, emptied-out stretch of coastline. Duke Energy, the area's biggest utility company, said that figure could rise to three million and restoring power could take weeks. The storm is some 645 kilometres wide. The flooding began on barrier islands in North Carolina and then spread into coastal and river communities there and in SC, swamping the white sands and golf courses in North Myrtle Beach.
Doll said that people living in low-lying areas next to streams, creeks and rivers, especially in farther inland areas, need to pay attention and evacuate in case rivers start flooding.
Two fins were spotted in the high water in Wilmington.
Forecasters said the storm will eventually break up over the southern Appalachians and make a sharp rightward swing to the northeast, its rainy remnants moving into the mid-Atlantic states and New England by the middle of the week.More news: Christina Aguilera upset she missed Cardi B's fight with Nicki Minaj
Heavy rains will continue to fall in the Carolinas and heavier rains are expected to spread into western parts of North Carolina, in addition to some parts of eastern Tennessee and eastern Georgia, Doll said.
In North Carolina, unrelenting rains were expected to swell the Cape Fear River to 62 feet next week, 3 feet higher than during Hurricane Matthew in 2016. That's enough to fill the Chesapeake Bay, or cover the entire state of Texas with almost 4 inches (10 centimeters) of water.
North Carolina alone is forecast to get 9.6 trillion gallons, enough to cover the Tar Heel state to a depth of about 10 inches.
In New Bern, population 29,000, flooding on the Neuse River left 500 people in peril.
A day after Florence blew ashore in North Carolina with 90 miles per hour (145 kph) winds, Coast Guardsmen, Marines and other rescue crews used helicopters, boats and heavy-duty vehicles to reach scores of people trapped on rooftops or otherwise caught in the floodwaters.
Volunteer rescue teams from across the country joined emergency responders in rescuing families trapped by the floodwaters. Hughes said the vehicle's roof is what struck the tree.More news: Klopp's Liverpool make solid case for the defence
"Honestly, I grew up in Wilmington. I love hurricanes. But this one has been an experience for me", she said.
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