Hurricane 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) on Thursday, the National Hurricane Center (NHC) said.
City officials in the state capital Tallahassee, which is in the path of the storm, said at least 70,000 homes were now without power.
Weather officials in the city warned of the risk of flash floods and urged people in the city to move to higher ground.
South of Tallahassee, the town of Cedar Key has seen a 9.6ft (2.9m) storm surge. 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.”
While the area is prone to storms and storm surges, it has not seen a hurricane in close to 4,000 days.
The last hurricane to strike Florida was Wilma in October 2005, which made landfall in the same year as Katrina and caused five deaths and an estimated $23bn (£17bn) of damage.
“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.
Some models show that the storm will stall near the New Jersey next week, potentially bringing prolonged heavy rain to the area.
Georgia Governor Nathan Deal has declared a state of emergency for 56 counties.