More than 60 people, including many children, were evacuated from a hotel in Jacksonville, North Carolina, after strong winds collapsed part of the roof.
Others were at home hoping for the best.
The centre urges people within the affected areas to take all necessary actions to protect life and property from rising water and the potential for other unsafe conditions.
As of 2:00 pm (1800 GMT), maximum sustained winds had weakened to 75 miles per hour (120 kph) but the National Hurricane Center (NHC) warned Carolina residents to be alert for life-threatening storm surges and "catastrophic freshwater flooding". "The larger and the slower the storm is, the greater the threat and the impact-and we have that".
The hurricane was "wreaking havoc" and could wipe out entire communities as it makes its "violent grind across our state for days", the governor said.
Roy Cooper, governor for North Carolina, said: "The sun rose this morning on an extremely unsafe situation and it's going to get worse".
"If this thing comes inland and stops in eastern North Carolina like they forecast it, and we get two days of continuous rain, the rain will be our biggest damage", he said.
Hurricane Florence has barrelled into the Carolina coast and moved inland, knocking down trees, overflowing rivers, dumping sheets of rain and leading to the death of five people before it was downgraded to a tropical storm still capable of wreaking havoc. "We are stuck in the attic".
Prior to Hurricane Florence's landfall, more than 1.7 million were ordered to evacuate the coast.
Some of the worst flooding was in New Bern, North Carolina, a town of about 30,000 people at the confluence of the Trent and Neuse rivers.
Hurricane Florence roared ashore Friday morning, bringing punishing winds and rains. Hundreds of thousands of people have evacuated the coast, more than 1500 U.S. flights have been cancelled, factories were shut and farmers rushed to save crops, poultry and pigs in anticipation of the storm. Significant weakening is expected over the weekend.
With a storm surge warning in effect, the authorities urge people to prepare themselves for the disaster.