There have been winds of 250km/h as the storm moves towards Cuba and US
Hurricane Irma is going to "devastate" parts of the United States, the country's Federal Emergency Management Agency (FEMA) has said, as the storm continues to cause major damage in the Caribbean.
Irma hovered over the Bahamas and the northern coast of Cuba on Friday.
The storm has been downgraded to a category four but is still packing winds of 250km/h as it rolls ominously towards Florida.
Thousands of tourists were evacuated from low-lying keys off the Cuban coast on Thursday after 20ft storm surges were predicted.
Irma battered British overseas territory the Turks and Caicos Islands early on Friday, causing communications to go down.
Its progress through the Cairbbean has left a trail of destruction
There has been severe damage to the British Virgin Islands, Barbuda and Anguilla.
More than half of the 1,400 people who live in Barbuda have been left homeless, and a two-year-old boy was killed as a family tried to escape.
Another island, St Martin, has been affected by the looting of televisions and other items.
Minister for France's overseas territories, Annick Girardin, described "scenes of pillaging" and wondered "how people can take advantage of the distress of others".
On its side of the Franco-Dutch island, the French government said four people had died and about 50 been injured.
Another two deaths and 11 injuries were reported on the Dutch side.
Two French frigates are expected to dock in St Martin on Friday. Aid and personnel have also been arriving from the nearby French island of Guadeloupe.
Two more hurricanes - Katia and Jose - have formed in the Atlantic region.
Donald Trump has warned that Irma has "absolutely historic destructive potential".
Urging Americans in the path of the storm to "be vigilant", President Trump said Irma would be unlike anything experienced before.
He said: "Nothing is more important than the safety and security of our people.
"We are doing everything we can to help with disaster preparations and, when the time comes, recover and rebuild together as Americans."
Meanwhile, FEMA chief Brock Long told reporters: "Hurricane Irma continues to be a threat that is going to devastate the United States in either Florida or some of the southeastern states."
He warned that parts of Florida would be out of electricity for days if not longer and that more than 100,000 people may need shelter.
America's National Hurricane Centre has warned of a "life-threatening storm surge and wind impacts to much of the state".
The storm is expected to reach Florida on Saturday.
Earlier, President Trump tweeted: "Hurricane Irma is of epic proportion, perhaps bigger than we have ever seen. Be safe and get out of its way, if possible. Federal G is ready!"
Our incredible U.S. Coast Guard saved more than 15,000 lives last week with Harvey. Irma could be even tougher. We love our Coast Guard!— Donald J. Trump (@realDonaldTrump) September 8, 2017