Tropical storm Hermine has made landfall in northern Florida, becoming the first hurricane to hit the state in 11 years.
Hermine hit the Florida Gulf Coast early on Friday as a category one hurricane, bringing with it a heavy storm surge.
Governor Rick Scott declared a state of emergency for 51 counties as residents were braced for the dangerous storm.
Wind gusts reached 80mph (130km/h), the National Hurricane Center (NHC) said.
Two hours after making landfall, as it moved inland, Hermine was downgraded to a tropical storm, the National Weather Service said.
Police in Taylor County, that has a population of more than 20,000, said the storm had inflicted “severe damage“.
City officials in the state capital Tallahassee, where people were urged to move to higher ground to avoid flash floods, said at least 70,000 homes were now without power.
South of Tallahassee, the town of Cedar Key saw a 6.6ft (two-metre) storm surge, raising high tide to almost 10ft. Images from the town posted on social media showed significant flooding.
“It is a mess… we have high water in numerous places,” Virgil Sandlin, the police chief in Cedar Key, told the Weather Channel. “I was here in 1985 for Hurricane Elena and I don’t recall anything this bad.”
“This is life threatening. We have not had a hurricane in years,” Governor Scott said.
He added that 8,000 members of the Florida National Guard were prepared to be deployed in the wake of the storm.
Mr Scott ordered evacuations in five counties in Florida’s north-west and called for voluntary evacuations in three other coastal counties.
“I’ve never seen it this high, it’s pretty damn crazy,” said Courtney Chason, who lives in the coastal town of Carrabelle. “I hope it doesn’t get any higher; we need lots of prayers.”
The city of St Petersburg near Tampa was littered with downed palm fronds and tree branches, and low-lying streets were flooded.
Weather officials predict Hermine will also hit Georgia and the Carolinas, and could bring heavy rains along the East Coast in the coming days.
Stacy Stewart of the National Hurricane Centre said there was a risk of tornadoes over the coming hours in those areas.
Georgia Governor Nathan Deal has declared a state of emergency for 56 counties.
Some models show that the storm will stall near the New Jersey coast next week, potentially bringing prolonged heavy rain to the area.