The third-strongest storm in recorded history to hit the mainland US has battered north-west Florida, flooding beach towns and snapping trees.
Hurricane Michael made landfall on Wednesday afternoon as a category four storm with 155mph (250km/h) winds in the state’s Panhandle region.
Two people, including a child, were killed by falling trees, officials say.
The storm left nearly 500,000 people without electricity in Florida, Alabama and Georgia, emergency services say.
Florida officials said a man was killed when he was crushed by a tree in Gadsden County.
A child died when a tree fell on a home in Seminole County, Georgia, CBS news reports.
Michael earlier reportedly killed at least 13 people as it passed through Central America: six in Honduras, four in Nicaragua and three in El Salvador.
Only the unnamed Labor Day hurricane, which hit Florida in 1935, and Hurricane Camille, which struck Mississippi in 1969, made landfall with greater intensity.
The Labor Day storm’s barometric pressure (the lower the number, the stronger the storm) was 892 millibars and Camille’s was 900, while Michael blew in with 919.
Michael was so powerful as it swept into Florida 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.
Only on Tuesday it was a category two hurricane but by Wednesday morning it had reached borderline category five, the highest level.
More than 370,000 people in Florida were ordered to evacuate, but officials believe many ignored the warning.
What happened in Florida?
The hurricane made landfall near Mexico Beach, Florida, at around 14:00 (18:00 GMT) on Wednesday, according to the NHC.
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.
The storm knocked out power to a quarter of a million homes and businesses, as power lines were smashed by falling trees.
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 National Weather Service (NWS) had issued a dramatic appeal for the people of the Florida state capital, Tallahassee, to heed warnings and leave their homes.
Schools and state offices in the area are to remain shut this week.
Florida has activated 3,500 National Guard troops.