A woman in Pender County, North Carolina, died from a heart attack after calling emergency services, as paramedics could not reach her because of fallen trees.
Video from Belhaven, North Carolina, showed storm-surge flooding up to the window-level of a house early Friday morning.
The mother and her baby were killed in New Hanover County when a tree fell on their house, the governor said, while confirming another death in Lenoir County.
Florence plowed into the Carolinas and lumbered slowly inland on Friday, knocking down trees, gorging rivers, dumping sheets of rain and leaving five people dead before it was downgraded to a tropical storm still capable of wreaking havoc. A 78-year-old man was electrocuted while trying to connect extension cords in the rain while another man died when he was knocked down by high winds while checking on his dogs.
"And since we're already on high ground, those two things together kind of help insulate us a little more than, I would say, others", she said.
Its top sustained winds have dropped to 70 miles per hour (110 kph), and it's at a near standstill, moving west at just 3 miles per hour (6 kph).
Firefighters and rescue crews pray in front of a home after removing a resident trapped inside during Hurricane Florence in Wilmington, North Carolina on September 14, 2018.
Nearly 20 inches of rain has already fallen.
By Friday night the center of the storm had moved to eastern SC, about 15 miles northeast of Myrtle Beach, with maximum sustained winds of 70 mph.
The White House said President Donald Trump was to visit hurricane-hit areas next week "once it is determined his travel will not disrupt any rescue or recovery efforts".
Officials said some 1.7 million people in the Carolinas and Virginia were warned to evacuate, but it's unclear how many did. By Friday evening, the eye of the storm had moved to SC.
New Bern resident Dan Eudy said he and his brother were awakened on Thursday night by the sound of a boat ramming against his front porch.
A police spokesperson told the news station that the family-of-three were trapped in the Wilmington home.