'Devastation' as Hurricane Irma slams Caribbean

One of the most powerful Atlantic storms on record, the dangerous Category Five hurricane was churning off the north coast of Puerto Rico on Wednesday night, on a potential collision course with south Florida where at-risk areas were evacuated.

The French part of St Martin -- a pristine resort known for its vibrant nightlife -- suffered the storm's full fury: at least six people died and 95 percent of dwellings were decimated, officials said.

"It's an enormous catastrophe. Ninety-five percent of the island is destroyed," top local official Daniel Gibbs said in a radio interview. "I'm in shock. It's frightening."

Guadeloupe prefect Eric Maire called the situation in St Martin "dramatic," saying the island -- which is divided between the Netherlands and France -- was without drinking water or electricity, and warning the death toll was almost certain to rise.

French President Emmanuel Macron earlier warned the final toll would be "harsh and cruel."

To the southeast, Barbuda, part of the twin island nation of Antigua and Barbuda, suffered "absolute devastation" with 95 per cent of properties damaged, and up to 30 per cent demolished, according to Prime Minister Gaston Browne.

"Barbuda now is literally rubble," Browne said. One person is known to have died on the island of 1,600 residents, apparently a child whose family was trying to get to safer ground.

Irma was packing maximum sustained winds of up to 185 mph (295 kph) as it followed a projected path that would see it hit the northern edges of the Dominican Republic and Haiti on Thursday, continuing past eastern Cuba before veering north for Florida.

As of 0000 GMT, the eye of the storm was just north of Puerto Rico and the hurricane was moving west-northwest at 26 kilometers per hour.

More than half of Puerto Rico's population of three million is without power, with rivers breaking their banks in the center and north of the island where Governor Ricardo Rossello activated the National Guard and opened storm shelters sufficient to house up to 62,000 people.

Blanca Santiago, who works in a beachside hotel in Puerto Rico's capital San Juan, described the howl of the wind whipping the coastline: "It was as if there were ghosts inside my home."

US President Donald Trump declared a state of emergency in Puerto Rico as well as the US Virgin Islands and Florida where he said the outlook was "not good."