Weak steering current will allow the hurricane to drift westward along the SC coast and inland, and center over the state's interior Sunday morning, the NHC projected.
For 62 years, Robert Faircloth has lived in Wilmington, North Carolina. The child's injured father was taken to a hospital.
Commenting on the threat, Governor Cooper said: "North Carolina, my message is clear: Disaster is at the doorstep, and it's coming in". A fourth victim was killed in Lenoir County while plugging in a generator, according to the governor's office. He apparently was blown down after he went outside to check on his hunting dogs, local media said.
Screaming winds bent trees and led to near-horizontal rain as Florence's leading edge whipped the Carolina coast to begin an onslaught that could last for days, leaving a wide area underwater from both heavy downpours and rising seas.
North Carolina Gov. Roy Cooper called Florence an "uninvited brute" that could wipe out entire communities as it grinds across the state.
It's unclear exactly how many people fled, but more than 1.7 million people in the Carolinas and Virginia were warned to clear out.
Police said 150 to 200 residents have been rescued earlier on Friday and 150 or more were still awaiting rescue. "We are stuck in the attic".
High winds and storm surge from Hurricane Florence hits Swansboro N.C., on September 14, 2018.
In Jacksonville, North Carolina, more than 60 people were evacuated from a hotel after part of the roof collapsed, city officials said.
The hurricane has torn buildings apart and knocked out power to more than 600,000 homes and businesses. Almost 2,100 flights have been canceled through Saturday.
The wind speed is now up to 155 kilometers per hour. It was expected to slowly move southwest into SC before turning north, forecasters said. He said parts of North Carolina had seen storm surges - the bulge of seawater pushed ashore by the hurricane - as high as 10 feet.
"Do you want to get hit with a train or do you want to get hit with a cement truck?" said Jeff Byard, an administrator with the Federal Emergency Management Agency.
Storm surge, the massive mound of water that builds up and comes ashore during a hurricane, is often the deadliest and most destructive threat from the storms.
The center of Florence will approach the coasts of North and SC on Thursday, then move near or over the coast of southern North Carolina and eastern SC on Thursday night and Friday, the NHC added.
A graphic of Hurricane Florence's path, generated today (Sept. 12) at 2 p.m. ET by the National Hurricane Center, shows an approximate representation of coastal areas under a hurricane warning (red), hurricane watch (pink), tropical storm warning (blue) and tropical storm watch (yellow).