The most powerful hurricane ever to hit north-west Florida has flooded beach towns, submerging homes and snapping trees like twigs.
Hurricane Michael made landfall on Wednesday afternoon as category three storm with 125mph (200km/h) winds in the state’s Panhandle region.
One person was killed by a falling tree, Florida officials say.
The storm left nearly 500,000 people without electricity in Florida, Alabama and Georgia, emergency services say.
Michael was so powerful that it remained a hurricane as it moved further inland.
Its rapid intensification caught many by surprise, although the storm later weakened.
Unusually warm waters in the Gulf of Mexico turbo-charged the storm from a tropical depression on Sunday.
It was a category two hurricane by Tuesday, and a borderline category five on Wednesday morning, packing 155mph winds.
Florida Governor Rick Scott warned of “unimaginable devastation”, saying it would be the worst storm in 100 years.
Michael reportedly killed at least 13 people in Central America: six in Honduras, four in Nicaragua and three in El Salvador.
More than 370,000 people in Florida were ordered to evacuate, but officials reckon many ignored the warning.
The coastal city of Apalachicola reported a storm surge of nearly 8ft (2.5m).
“We are catching some hell,” Timothy Thomas, who rode out the storm with his wife in their home in Panama City Beach, Florida, told the Associated Press news agency.
“We are in new territory,” Miami-based National Hurricane Center (NHC) meteorologist Dennis Feltgen wrote on Facebook.
“The historical record, going back to 1851, finds no Category 4 hurricane ever hitting the Florida panhandle.”
Reuters news agency reports that Michael is the third-most powerful storm ever to make landfall in the mainland US, after Hurricane Camille in Mississippi in 1969 and the Labor Day hurricane of 1935 in Florida.
Federal Emergency Management Agency Director Brock Long said at the White House that he was especially concerned about buildings constructed before 2001, and not able to withstand such high winds.
“We just hope those structures can hold up,” President Donald Trump responded. “And if not, that they’re not in those structures.”
States of emergency have been declared in all or parts of Florida, Alabama, Georgia and North Carolina.
The hurricane made landfall near Mexico Beach, Florida, at around 14:00 (18:00 GMT) on Wednesday, according to the NHC.
Forecasters warned parts of Florida could experience storm surges of up to 14ft (4m) and flash floods from up to 12in (30cm) of rain.
Schools and state offices in the area are to remain shut this week.
Florida has activated 3,500 National Guard troops.
At 03:00 GMT on Thursday, maximum sustained winds decreased to 75mph, the NHC said in a bulletin.
“Michael will steadily weaken as it crosses the south-eastern United States through Thursday night, becoming a tropical storm by Thursday morning.
“Michael is forecast to re-strengthen some Thursday night and Friday when it moves off the east coast of the United States and becomes a post-tropical cyclone on Friday,” the NHC added.
Countdown on for world’s longest non-stop flight
The battle to offer the world’s longest non-stop flight steps up a gear on Thursday, when a new Singapore-to-New York service takes off.
Singapore Airlines is relaunching the service five years after it withdrew because it had become too expensive.
It will cover more than 15,000km and is scheduled to take just under 19 hours.
Qantas launched a 17-hour non-stop service from Perth to London earlier this year, while Qatar runs a 17.5-hour service between Auckland and Doha.
The flight from Changi Airport to Newark’s international airport will be taking off amid much fanfare and with barely a seat to spare.
Singapore Airlines (SIA) said there was demand for customers for non-stop services which help cut travelling times compared with flights which have a stopover.
The airline told the BBC that business class seats for the flight were fully booked.
However, there were “a very limited number” of premium economy seats left.
The airline is not planning to offer any economy bookings on the route.
A business class ticket will entitle passengers to two meals, and the choice of when they are served, plus refreshments in between. They will also have a bed to sleep in.
Premium economy fares will get three meals at fixed times, with refreshments in between.
The brand new Airbus plane that SIA is using has been configured to seat 161 passengers in all – 67 business passengers and 94 premium economy passengers.
“The thinking behind that is that they are selling a premium product – it’s for the top end of town,” says aviation expert Geoffrey Thomas, who will be on board Thursday’s flight.
“This is a route between two massive financial hubs, and so they will fill this plane up with business people, or well-heeled travellers who want the convenience of a non stop flight.
“It’s also been proven that when carriers introduce a new non-stop route, the traffic on that route increases threefold.”