At least one person was killed and "several were injured" after Hurricane Irma raged over Dutch Sint Maarten in the Caribbean, Internal Affairs Minister Ronald Plasterk said Thursday.

Hurricane Jose, a Category 1 storm packing winds of about 135 kilometers per hour (85 miles per hour), is approaching the Caribbean hot on the heels of Irma, but will likely bypass land, according to the French weather service.

Hurricane Irma will have a "truly devastating" impact when it slams into southern coastal areas of the United States, the head of the US emergency agency said on Thursday

"The majority of people along the coast have never experienced a major hurricane like this. It will be truly devastating," Federal Emergency Management Agency (FEMA) chief Brock Long told CNN.

Britain is sending two military vessels to help victims of Hurricane Irma and is earmarking £32 million ($41.8 million, 34.8 million euros) in aid, the government said Thursday.

Hurricane Irma, rampaging across the Caribbean towards the Bahamas and south Florida, is smashing not only homes and hotels but weather records as well.

The French part of the Caribbean island St Martin is "95 percent destroyed" after Hurricane Irma tore through the region, top local official Daniel Gibbs said late Wednesday.

Hurricane Irma will exact a "heavy, cruel" toll on two French Caribbean islands, President Emmanuel Macron said Wednesday after a crisis meeting with key ministers in Paris.

Hurricane Irma has already caused "major damage" on several Caribbean islands, French Overseas Territories Minister Annick Girardin said on Wednesday.

Irma, a still strengthening and dangerous Category Four hurricane, churned toward the Leeward Islands early Tuesday, sparking alarm and alerts from the Caribbean to Florida, which declared an emergency.

Climate change will dominate discussions when the leaders of vulnerable Pacific nations hold their annual meeting in the Samoan capital Apia this week, with global warming threatening their existence, officials say.