Tragedy struck one family when a tree fell on a house; a mother and child were killed. The father was transported to a hospital for treatment.
Almost 300,000 customers in North Carolina were meanwhile reported to be without power as the outer band of the storm approached.
Hurricane Irma destroyed Kathy Griffin's house in Florida a year ago, and it could be days before she finds out whether Florence smashed her fifth-story condominium in Wrightsville Beach, where authorities said utilities could be out for days or weeks.
Two people in Lenoir County were killed: a 78-year-old Kinston man who was electrocuted when connecting extension cords in the rain and a 77-year-old man who was blown down by the wind when he went to check on his hunting dogs. And a man was knocked to the ground while outside and died, authorities said. "Hurricane Florence is going to continue its violent grind across our state for days".
Donald Trump was to visit hurricane-hit zones "early to the middle of next week", the White House said, "once it is determined his travel will not disrupt any rescue or recovery efforts".
Florence is also forecast to drench parts of the Carolinas with as much as 40 inches of rain, producing catastrophic flash flooding, according to an advisory from the National Hurricane Center (NHC). Floodwaters submerged U.S. Highway 264, cutting off a major route to other flood-prone areas along the river and the adjacent Pamlico Sound.
"We're deeply concerned for whole communities which could be wiped away".
Both rivers overflowed their banks, flooding homes, stores and streets and trapping many people in their houses. We were forced to have conversations with these people and say hey, do you by chance live in a two-story home?
Governor Cooper said no fatalities had been reported yet but there have been "several hundred" rescue operations and "there are still some people they need to get to".
Devastating flooding has already affected the area, with storm surge reaching up to 10 feet, officials said.
Meteorologist Ryan Maue of weathermodels.com said Florence could dump a staggering 18 trillion gallons of rain over a week on North Carolina, South Carolinas, Virginia, Georgia, Tennessee, Kentucky and Maryland.
Man killed by shark in Massachusetts' first fatal attack for 80 years
The unidentified swimmer was reportedly in the water off of Cape Cod's Newcomb Hollow Beach when he was attacked around noon. Great white sharks - one of the ocean's most feared predators - are found in waters off Cape Cod.
But Jeff Byard of the Federal Emergency Management Agency says saving lives is the priority, and anyone fearing for their safety should call 911 for help.
Forecasters said that given the storm's size and sluggish track, it could cause epic damage akin to what the Houston area saw during Hurricane Harvey just over a year ago, with floodwaters swamping homes and businesses and washing over industrial waste sites and hog-manure ponds.
Metal signs and roof coverings littered the biggest commercial byway, Market Street, and trees blocked many roads.
"Some of the rainfall totals we're getting are already adding up to about 14 inches", NHC Director Ken Graham said shortly after 11 a.m. ET.
"Hurricanes normally come in and they go inland, which sucks the power out of them as they go over the land", he said.
A woman died from cardiac arrest in the town of Hampstead after emergency responders had their route to her blocked by downed trees, a county official said.
Hurricane-force winds extend outward up to 35 miles (55 kilometers) from the center and tropical-storm-force winds extend outward up to 170 miles (280 kilometers).
Kathy Griffin was hunkering down Friday in a hotel in Wilmington, North Carolina with her husband. Wilmington Deputy Fire Chief Steve Mason said the victims died at the scene.
"Hurricane Florence is powerful, slow and relentless", Cooper said.
"I think we kind of let our guards down", he said of his community's response to the storm's being downgraded to Category 2 from 4.
"Our house is on high ground so we're not anxious about the flooding", he said.