Hurricane Florence has made landfall on the US East Coast, knocking out power to half a million homes and causing buildings to crumble.
The centre of the storm struck Wrightsville Beach in North Carolina, with gales of up to 90mph (150 km/h).
Rains and surging seas have already inundated coastal areas. Dozens of people were rescued from a collapsing hotel in North Carolina overnight.
Evacuation warnings are in place for 1.7 million people.
North Carolina Governor Roy Cooper said surviving the storm would be a test of "endurance, teamwork, common sense and patience".
"This is an uninvited brute that just won't leave," he told NBC on Friday.
National Weather Service forecaster Brandon Locklear said North Carolina is likely to see eight months of rain in two to three days.
Thousands of miles away, meanwhile, a huge typhoon is moving towards the Philippines. More than five million people are in the path of Super Typhoon Mangkhut, officials say.
Conditions deteriorated on Friday as slow-moving Hurricane Florence crawled along at 6mph (9.5km/ h).
Its wind speeds had lowered slightly on Thursday night, making it a category one hurricane.
But the National Hurricane Center says the tempest remains extremely dangerous because of the high volume of rainfall and predicted storm surges.
By Friday morning, the North Carolina coastal town of Atlantic Beach had already received 30in (76cm) of rain, the US Geological Service said.
The storm is forecast to dump about 18 trillion gallons of rainwater on US soil, most of it in North Carolina, meteorologist Ryan Maue tweeted.
Hurricane Harvey last year dumped some 33 trillion gallons of rainwater in the US.
More than 497,000 homes and businesses are already without power, and energy companies warn up to three million homes and businesses could lose electricity.
Officials have warned restoring electricity could take days or even weeks.
In Jacksonville, North Carolina, officials rescued about 60 people overnight from a hotel that was collapsing in the storm.