Days ahead of the storm, about 1.7 million people in North Carolina, South Carolina and Virginia were warned to evacuate before its outer bands reached the coast Thursday.
At landfall, Florence was a Category 1 hurricane with maximum sustained winds of 90 miles per hour. By 5 p.m., it was about 50 miles west-southwest of Wilmington, and the wind had dropped to 70 mph.
More than 80,000 people in North Carolina already were without power as the storm began buffeting the coast, and more than 12,000 were in shelters.
The Navy says nearly 30 Virginia-based ships and 128 aircraft sent away from their bases in the Hampton Roads-area because of now-Tropical Storm Florence have been given the go-ahead to return.
Florence peaked at a terrifying Category 4 with top winds of 140 mph (225 kph) over warm ocean water before making landfall as a Category 1 hurricane at 7:15 a.m.at Wrightsville Beach, a few miles (kilometers) east of Wilmington and not far from the SC line.
More ominously, forecasters said the onslaught would last for hours and hours because Florence was barely creeping along at 6 mph (9 kph) and still drawing energy from the ocean.
The Miami-based center says Florence is bringing "catastrophic" fresh water flooding over a wide area of the Carolinas.
Despite a mandatory evacuation ordered Tuesday, emergency officials in New Bern reported that about 150 people were waiting to be rescued, and two Federal Emergency Management Agency teams were in the area, the News & Observer of Raleigh, NC, reported.
"A basketball sized hole was found in a corner room by an Officer", officials said. "You're going to have flooding miles and miles inland", the center's director, Ken Graham, said Friday morning.
Rescue workers are scrambling to rescue 150 people trapped by rising flood waters in the coastal city of New Bern, North Carolina.
The city installed 11 pumps to help deal with the river, but Mayor John Cantey said he wants people living near it to get out. Roberts said numerous residents live near the Neuse and Trent rivers. At least four people have died, a toll authorities fear will rise as the storm crawls westward across SC.
"WE ARE COMING TO GET YOU", a tweet from the city overnight said.
"We are completely ready for hurricane Florence, as the storm gets even larger and more powerful".
Forecasters said conditions will continue to deteriorate as the storm pushes ashore early Friday near the North Carolina-South Carolina line and makes its way slowly inland.
As of noon, Emerald Isle had over 23 inches of rain, and Wilmington and Goldsboro had about a foot. Its forward movement was 6 miles per hour.
The combination of a risky storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. This is expected to cause "catastrophic flash flooding and prolonged significant river flooding".
The hurricane center 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 next week.
Hurricane Florence is set to inundate nearly all of North Carolina in several feet of water, State Governor Roy Cooper told a news conference, while National Weather Service forecaster Brandon Locklear predicted up to eight months' worth of rain in two or three days.
Florence was seen as a major test for FEMA, which was heavily criticized as slow and unprepared past year for Hurricane Maria in Puerto Rico, where the storm was blamed for almost 3,000 deaths in the desperate months that followed.
Screaming winds bent trees and raindrops flew sideways as Florence's leading edge battered the Carolina coast Thursday.