"This is the largest such evacuation in the history of the country", Prime Minister Hubert Minnis said. Power was knocked out there and on Saint Barthelemy. Jonathan Falwell, a pastor from Lynchburg, Virginia and son of late televangelist Jerry Falwell, was on St. Martin as the storm hit and shared photos of the destruction on Twitter.
The hurricane is expected to pass Hispaniola, Turks and Caicos and southeastern Bahamas later today, according to the US National Hurricane Center (NHC).
About 60% of Barbuda's 1,400 residents are homeless after the storm flooded practically the whole island, Browne said.
"We'll see what happens", President Donald Trump said in Washington.
"Should we leave? A lot of people that I wouldn't expect to leave are leaving".
Parkinson adds that although it appeared Irma had hit peak intensity earlier, it is going through another eyewall replacement cycle, which means the strongest winds will extend further from the storm.
In the United Kingdom, the government said Irma inflicted "severe and in places critical" damage to the British overseas territory of Anguilla.
It is only the second time anywhere in the world a storm has been recorded maintaining such windspeeds for more than 24 hours, after typhoon Haiyan in 2013, according to an expert at the University of Colorado.
By early Thursday, the National Hurricane Center said the center of the storm was about 140 miles northwest of Puerto Rico, and moving west-northwest at 17 mph in the direction of the island of Hispaniola.
More than 600,000 people are without power and almost 50,000 without water on the island, with at least 14 hospitals using generators after losing power.
Weather forecasters have described Irma as a "potentially catastrophic" Category 5 storm, the highest US classification for hurricanes.
The coast is still repairing millions of dollars of damage done Hurricane Matthew in 2016.
Branson, owner of Virgin Airlines and Virgin Media, among other interests, had tweeted ahead of the storm that he would be hunkering down with guests in a concrete wine cellar underneath his house on Necker Island to ride out the storm, which is now confirmed to be the most powerful hurricane to ever form in the Atlantic.
Governor Rick Scott declared a state of emergency across the whole state on Monday in preparation for a possible landing this weekend.