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.
How powerful was Michael when it hit?
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.
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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).