Residents in the Florida Keys have been ordered to leave their homes as Hurricane Irma could slam into the US sunshine state within days.

People in low-lying areas in highly populated Miami-Dade County were urged to move to higher ground in preparation for the storm, which is currently the maximum category five.

The most powerful Atlantic Ocean hurricane ever recorded has been causing havoc in the Caribbean, including the Virgin Islands and Puerto Rico, which are being hit by winds up to 185mph.

At least six people have been killed on the island of St Martin, according to Guadeloupe prefect Eric Maire.

St Barts and Barbuda also reported casualties, the latter being that of a two-year-old.


Image: Puerto Rico is being pounded by Hurricane Irma

Another hurricane, Jose, is also heading for the Caribbean and tropical storm Katia was upgraded to a hurricane in the Gulf of Mexico.

Hurricane Irma is on a path towards the Dominican Republic, Haiti and Cuba before possibly heading for Florida over the weekend, but its precise direction is uncertain.

Florida governor Rick Scott said it could be more devastating than 1992's Hurricane Andrew, a category five storm that is the most destructive ever to hit the state.

Image: Preparations are under way in Florida for Hurricane Irma

The eye of Irma first roared over Barbuda, also hitting the nearby island of Antigua.

St Barts and St Martin were next to be struck, as low-lying areas flooded, according to the French weather office.

:: IRMA LIVE: Latest updates as Caribbean islands hunker down

Hurricane Irma batters Anguilla

All government buildings on the French-run side of the island of St Martin had been destroyed, according to French interior minister Gerard Collomb.

"We know that the four most solid buildings on the island have been destroyed which means that more rustic structures have probably been completely or partially destroyed," he told reporters.

French overseas territories minister Annick Girardin said Irma had caused "major damage" on several islands.

According to some weather experts, the hurricane covers an area bigger than the UK and Ireland.

The weather station on St Barts measured winds of 151mph before its monitoring equipment was destroyed by the storm.

Hurricane Irma as seen from space

"We are hunkered down and it is very windy... So far, some roofs have been blown off," said Garfield Burford from Antigua and Barbuda's ABS TV and Radio.

Most people were without power and around 1,000 people on Antigua were spending the night in shelters, Mr Burford said.

"It's very scary... most of the islands are dark, so it's very, very frightening," he added.

The wind sent debris flying as people huddled in their homes, many of which do not have concrete foundations and only wooden roofs.

Image: The Virgin Islands were hit by the hurricane

Tourists in the area were evacuated on Tuesday before the hurricane arrived.

British Airways sent an empty aircraft to the region, bringing 326 customers back to the UK, and a Virgin Atlantic flight left Antigua five hours early to avoid the storm.

The Foreign Office said Britons should follow the advice of authorities and heed evacuation orders.

President Trump has declared emergencies in Florida, Puerto Rico and the US Virgin Islands.

If it hits Florida it will be the second powerful storm to hit the US mainland in two weeks after Hurricane Harvey caused devastation and led to the deaths of 70 people.