Wind and rain from Hurricane Hermine slammed Florida's northern Gulf Coast before it weakened to a tropical storm and ploughed its way overland toward the Atlantic Coast on Friday.
Hermine made landfall early on Friday, bringing heavy rains and packing winds of 80 mph (130 km/h), causing damage and leaving tens of thousands of households without power along Florida's Gulf Coast.
"It is a mess... we have high water in numerous places," Virgil Sandlin, the police chief in Cedar Key, Florida, told the Weather Channel.
Strong gusts downed power lines and trees as widespread flooding inundated communities in Florida before the hurricane weakened into a tropical storm as it reached Georgia and South Carolina, where conditions deteriorated early on Friday morning.
"The combination of a dangerous storm surge and the tide will continue to cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the National Hurricane Center said.
The center warned that some areas along Florida's northern Gulf Coast may experience 9 feet (3 m) of flooding.
Florida Governor Rick Scott said the storm could lead to deaths and told residents to stay indoors until it had passed.
Pasco County reported crews rescued 18 people and brought them to shelters after their homes were flooded in Green Key and Hudson Beach early on Friday.
"Stay indoors even if it calm outside. The eye of Hermine may be passing through. Let it pass completely before surveying any damage," Governor Scott advised residents in a Twitter post.
Hermine became the fourth hurricane of the 2016 Atlantic storm season. By 11 p.m. EDT, maximum winds were listed at 80 mph (130 kph), with hurricane-force winds extending up to 45 miles (75 km) from the storm's center.
Hermine could dump as much as 20 inches (51 cm) of rain in some parts of the state. Ocean storm surge could swell as high as 12 feet (3.6 meters).
Scott declared a state of emergency in 51 of Florida's 67 counties, and at least 20 counties closed schools.
Mandatory evacuations were ordered in parts of five counties in northwestern Florida, with voluntary evacuations in at least three more counties. Twenty emergency shelters were opened across the state for those displaced by the storm.
"This is life-threatening," Scott told reporters on Thursday.
In coastal Franklin County, people were evacuated from barrier islands and low-lying shore areas.
"Those on higher ground are stocking up and hunkering down," Pamela Brownlee, the county's emergency management director, said.
The National Weather Service issued tornado and tropical storm watches and warnings for communities throughout northern Florida and north along Atlantic Coast, where it posed a Labor Day weekend threat for tens of millions of people.
On its current path, the storm also could dump as much as 10 inches (25 cm) of rain on coastal areas of Georgia, which was under a tropical storm watch, and the Carolinas. Forecasters warned of "life-threatening" floods and flash floods there.
The governors of Georgia and North Carolina on Thursday declared emergencies in affected regions. In South Carolina, the low-lying coastal city of Charleston was handing out sandbags.
(Additional reporting by Brendan O'Brien in Milwaukee, Laila Kearney in New York and Jon Herskovitz in Austin, Editing by Angus MacSwan)