Hurricane Florence is making landfall after thrashing the Carolinas all night long with devastating flooding and damaging winds.
SC ordered the mandatory evacuation of one million coastal residents while North Carolina announced an evacuation of the Outer Banks, a popular tourist destination.
Florence's rain will be relentless, with up to 40 inches expected in some parts of the Carolina coasts, forecasters said.
And the storm is still expected to bring catastrophic winds, rain, storm surges and flooding, the National Hurricane Center briefing said.
The Weather Channel produced a terrifying Hurricane Florence weather forecast using a visualization to show the horrifying reality of what 9-foot flood waters might look like in North Carolina. "We are stuck in the attic".More news: Trump denies 3,000 Puerto Ricans died due to Hurricane Maria, blames Democrats
Forecasters are warning the storm surge is life threatening and will be even worse at high tide. Hurricane-force winds extended 130 kilometres from its centre, and tropical-storm-force winds up to 315 kilometres.
"Surviving this storm will be a test of endurance, teamwork, common sense and patience", he warned.
At least 12,000 people had taken refuge in 126 emergency shelters, Governor Cooper said, with more facilities being opened. Another 400 people were in shelters in Virginia, where forecasts were less dire.
About 1.7 million people in North Carolina, South Carolina and Virginia are under voluntary or mandatory evacuation orders and millions of others live in areas likely to be affected by what officials called a "once in a lifetime" storm.
"WE ARE COMING TO GET YOU", New Bern city officials said on Twitter.
New Bern Mayor Dana Outlaw said about 200 people have been rescued so far. He could not yet confirm whether there were injuries or fatalities. "We were able to evacuate quite a few; some did not go", he said.More news: EU's Juncker wants bigger global role for euro
The rescues began around 4 p.m. Thursday, Craven County spokeswoman Amber Parker said.
Florence could bring wind-driven storm surges of seawater as high as four metres and NHC Director Ken Graham said on Facebook they could push in as far as three kilometres. Then Florence may hover over the region for days, with cloud cover as wide as the Carolinas.
In its 0300 GMT advisory, the National Hurricane Center said the maximum sustained winds of Florence were 90 miles per hour (150 kilometers per hour), dropping it to the weakest of five categories on the Saffir-Simpson scale.
Coastal streets were inundated with ocean water, causing damage to dozens of homes and businesses, officials said.
Florence was seen as a major test for FEMA, which was heavily criticized as slow and unprepared past year for Hurricane Maria in Puerto Rico, which was blamed for almost 3,000 deaths.
FEMA's first priority after Florence passes will be getting infrastructure that's critical to communities' well-being up and running, Long said.More news: As Hurricane Florence nears, live surf cam videos show impact on Carolinas