The Category 1 hurricane, with punishing winds and dumping 3 inches of rain an hour, made landfall at 7:15 a.m. ET near Wrightsville Beach, just east of Wilmington.
Florence's center may linger for another whole day along coastal North and South Carolina -- punishing homes with crushing winds and floods and endangering those who've stayed behind.
In the besieged North Carolina city of New Bern, rescuers by midmorning Friday had plucked more than 200 people from rising waters, but about 150 more had to wait as conditions worsened and a storm surge reached 10 feet, officials said.
"In a matter of seconds, my house was flooded up to the waist, and now it is to the chest," said Peggy Perry, who along with three relatives, was trapped early Friday in her New Bern home. "We are stuck in the attic."
Officials urged residents there to take shelter at the highest points of their homes, including rooftops.
Florence's rain will reach 40 inches in some parts of the Carolinas, forecasters said. Rainfall totals will be similar to those in hurricanes Dennis and Floyd in 1999, Chris Wamsley of the National Weather Service said Friday morning.
"The only difference is, back then it was within 14 days," he said. With Florence, "we're looking at the same amount of rainfall in three days."
"This is not the end of it," Jeff Byard of FEMA added, noting that heavy rain and surge will continue for another 24 to 36 hours. "Those citizens that did not heed the evacuation warnings, it's time to stay where you are and do the best you can" to protect yourself and your family.
By Friday morning, Florence already had:
• Sapped power to more than 500,000 customers in North and South Carolina, emergency officials said.
• Forced 26,000 people into more than 200 emergency shelters across the Carolinas.
• Forced more than 60 people to evacuate a hotel in Jacksonville, North Carolina, after part of the roof collapsed, city officials said.
• Canceled more than 1,100 flights along the East Coast on Friday and Saturday.
Hours earlier, streets along the coast had been transformed into raging streams, and massive waves surged along the Outer Banks.
"There's already water (in the) bottom part of people's houses," Todd Willis, who lives in Kennel Beach, North Carolina, said Thursday night. "This is just the beginning."