In the state's Pender County, a woman died of a heart attack; paramedics trying to reach her were blocked by debris.
A fourth person reportedly was killed while plugging in a generator in the state's Lenoir County, according to U.S. media.
Hurricane Florence is poised to hit the mid-Atlantic coast and the Carolinas this week, and satellite images of the storm are nothing short of terrifying.
Florence was downgraded to a tropical storm by the National Hurricane Centre (NHC) but authorities warned the danger was far from over.
Right now, the National Oceanic and Atmospheric Administration's National Hurricane Center is predicting that Florence will become a tropical storm tomorrow (Sept. 15) over SC, continue northwest to eastern Kentucky, then swing northeast and track over most of New England early next week.
But forecasters said its extreme size meant it could batter the US East Coast with hurricane-force winds for almost a full day.
The NHC described Florence as a "slow mover" and said it had the potential to dump historic amounts of rainfall on North and SC, as much as 40 inches (one meter) in some places.
Maysie Baumgardner, 7, sheltered with her family at the Hotel Ballast in downtown Wilmington as Florence's floodwaters filled the streets. "You may need to move up to the second story, or to your attic, but WE ARE COMING TO GET YOU", the authorities in New Bern said on Twitter.More news: Tennis Umpires reportedly considering Boycott of Serena Williams Matches
Forecasters said Florence's surge could cover all but a sliver of the Carolina coast under as much as 11 feet (3.4 meters) of sea water.
Twenty inches were reported by early Friday afternoon in the town of Oriental.
To the south, storm surge pushed water levels at Johnny Mercer Pier at Wrightsville Beach, where Florence made landfall at 7:15 a.m. with 90 miles per hour winds, to more than 8.5 feet.
More than 1 million people had been ordered to evacuate the coasts of the Carolinas and Virginia and thousands have moved to emergency shelters. But it was clear that this was really about the water, not the wind.
Bertha Bradley said she has never favored evacuating ahead of hurricanes.
Another moving photograph captured a K-9 handler giving his dog, Tag, fluids through an IV bag to keep him healthy while conducting important search and rescue work in Pembroke, North Carolina.
Governor Cooper said the state would arrange a visit by Trump "at an appropriate time".