Hurricane Dorian has made landfall in the north-west Bahamas as a monster category five storm with sustained winds of up to 180mph (285km/h).
The “extremely dangerous” storm is the strongest hurricane on modern record in the area, the US National Hurricane Center (NHC) says.
Grand Bahama residents have been evacuating from its predicted path.
A storm surge could be life-threatening and as high as 23ft (7m) in places, officials warn.
The storm made landfall at 12:40 (16:40 GMT) on Elbow Cay in the Abaco islands, northern Bahamas, the NHC said.
Local residents posted footage showing floodwaters engulfing some homes, their rooftops blown off.
Dorian, moving westward at 7mph, is expected to continue to move over Great Abaco Island and near, or over, Grand Bahama Island later on Sunday into Monday.
Authorities closed some airports in the outlying islands, but the main international airport remains open on Sunday.
After hitting the Bahamas, it should move closer to the Florida east coast late on Monday through Tuesday night local time.
US President Donald Trump said he was monitoring Dorian. He cancelled a planned trip to Poland, sending Vice-President Mike Pence in his place.
In a tweet on Sunday, Mr. Trump warned Dorian was expected to hit “much” harder than originally thought, and urged residents in its path to be careful.
Hurricanes, which vary in strength from category one to five on the Saffir-Simpson scale, tend to get stronger as they move over warm waters like those off the coast of Florida.
Dorian has also grown larger in size, with hurricane-force winds currently extending 45 miles (75km) from the storm’s centre.
Florida was earlier expected to take a direct hit in the storm. Its governor, Ron DeSantis, has activated 2,500 National Guard troops and has another 1,500 on standby.
As Dorian crawled towards the US, shoppers were seen queuing around blocks to buy supplies such as medication and fuel.
Popular attractions, including Disney World in Orlando, have said they are “closely monitoring” the storm.
The coastal city of Miami has also ordered the removal of electric rental scooters from the streets to avoid them becoming projectiles.
Palm Beach and Martin counties issued mandatory evacuations for some residents, including for those in mobile homes, barrier islands and low-lying areas.
