More than a million people along the coastlines of North Carolina, South Carolina and Virginia have been ordered to evacuate.
Coastal streets flowed with ocean water, and more than 460,000 homes and businesses were without power, mostly in North Carolina, according to poweroutage.us, which tracks the nation's electrical grid.
Some parts of North Carolina have already seen surges as high as 10ft in places.
The monster storm could dump drenching rains of up to one meter.
By Friday evening, the eye of the storm had moved to SC. "Hurricane Florence is going to continue its violent grind across our state for days".
Florence peaked at a terrifying Category 4 with top winds of 140 mph over warm ocean water before making landfall as a Category 1 hurricane at 7:15 a.m.at Wrightsville Beach, a few miles east of Wilmington and not far from the SC line.
"The cost to SC, if that happens, if the storm continues the way it is going, could be in the billions", Dahler said.
The National Hurricane Center (NHC) downgraded it to a tropical storm on Friday, but warned it would dump as much as 30 to 40 inches (76-102 cm) of rain on the southeastern coast of North Carolina and part of northeastern SC. Morehead City, North Carolina, had received 23 inches (58 centimeters) of rain by Friday night with more torrents on the way.
Super Typhoon Mangkhut tore through the northern tip of the Philippines on Saturday packing winds of more than 200 km per hour (124 mph) along with torrential rain, killing three people and causing floods, landslides and power outages.
"This is going to be a very trying period for the state", he said."We're liable to have flash floods, bridges and roads washed out". For those wishing to track Florence's devastation from miles away, PBS NewsHour has compiled this guide of sources that we will be closely monitoring as the storm progresses.
Authorities warned, too, of the threat of mudslides and the risk of an environmental disaster from floodwaters washing over industrial waste sites and hog farms.
Strong winds and heavy rain continue to present a danger, and Florence is now being attributed to several deaths.
The center of the hurricane´s eye came ashore at about 7:15 a. m. EDT (1115 GMT) near Wrightsville Beach close to Wilmington, with sustained winds of 90 miles per hour (150 kph), the National Hurricane Center (NHC) said. That's enough to fill the Chesapeake Bay, or cover the entire state of Texas with almost 4 inches of water.
North Carolina alone is forecast to get 9.6 trillion gallons, enough to cover the Tar Heel state to a depth of about 10 inches.
Meanwhile, many were experiencing a complete blackout as the storm damaged infrastructure, utility poles and transmission lines.
In Jacksonville, North Carolina, city officials posted photos of toppled gas pumps and a downed trees early Friday, warning residents to take shelter and avoid roadways.
In New Bern, population 29,000, flooding on the Neuse River left 500 people in peril.
"WE ARE COMING TO GET YOU", the city tweeted during the height of the storm. "We are stuck in the attic".
Courageous volunteers are seen defying the danger and continuing to rescue residents and their pets.
Eudy said his family stayed in their home partly to protect their house. "I love hurricanes. But this one has been an experience for me", she said.