Hurricane Irma damage considerable - Macron

Hurricane Irma has caused considerable damage on French island territories in the Caribbean, and casualties are expected, France's president says.

The impact of Irma on St Martin and St Barts would be "hard and cruel", Emmanuel Macron added.

His overseas affairs minister later confirmed at least two people dead and another two seriously injured.

The storm damaged more than 90% of buildings on Barbuda, Antigua and Barbuda's prime minister said.

The category five hurricane, the highest possible level, is now passing over the northern Virgin Islands.

The most powerful storm in a decade, with wind speeds of 295km/h (185mph), is also forecast by the US National Hurricane Center to pass near or just north of Puerto Rico, then near or just north of the coast of the Dominican Republic on Thursday.

Flooded streets in Saint Martin

Hurricane Irma first hit Antigua and Barbuda, before moving on to St Martin and Saint Barthélemy - the French holiday destination popularly known as St Barts.

Significant damage is also being reported in the Dutch section of St Martin, known as Sint-Maarten.

French Interior Minister Gérard Collomb said the hurricane had caused major floods, and destroyed buildings, including four of the "most solid" on the island.

• Hurricane Irma: All you need to know

• The world's most powerful storms

• How do you calculate the cost of a hurricane?

Thousands of people have been evacuated from at-risk areas across the Caribbean. Residents have flocked to shops for food, water, and emergency supplies, and airports have closed on several islands which are popular holiday destinations.

British Foreign Secretary Boris Johnson said the government was in touch with British overseas territories caught up in Irma, and was doing "everything we can to help those afflicted".

In the US, Florida's Key West area has ordered a mandatory evacuation, with landfall expected at the weekend.

Irma as seen from space at 11:30 GMT on Wednesday

The French government said earlier it was worried about thousands of people who had refused to seek shelter on the islands.

Officials in the French territory of Guadeloupe confirmed the following damage:

• On St Barts, the fire brigade station has been flooded with a metre of water, with engines out of service and crews sheltering on an upper floor; there is a total power blackout; many roofs have been blown off

• On St Martin, the prefecture building has been partially destroyed, with the prefect (chief officer) and 23 other people sheltering in a secure room; the fire station is out of order; there is a power blackout; several roofs at the police station have been blown off

In the Dutch territory, known as Sint-Maarten, the airport has been closed with photos showing debris strewn across the departures area and outside.

There has been a total power blackout, streets are littered with debris, cars are underwater and boats in the ports have been destroyed, Dutch broadcaster NOS reported (in Dutch).

France's interior minister said three emergency teams were being sent to the islands, two from France and one from Guadeloupe.

• Britons evacuated as Irma hits

• Flights cancelled as Irma approaches

• Hurricane Irma: A visual guide

Confirming the two fatalities in St Martin and St Barts, French Overseas Affairs Minister Annick Girardin said: "Obviously the situation can change very quickly."

The hurricane had caused major flooding in low-lying areas, and authorities had yet to gain access to the worst-hit areas, she added.

Some 40,000 people live in the French part of St Martin, with around the same number estimated to live on the Dutch side. About 9,000 people live on St Barts.

Islands in Irma's immediate path

Antigua and Barbuda

• Population: 90,800

• Key facts: one of the Caribbean's most prosperous nations, thanks to its tourism industry and offshore financial services

• Hurricane report: Antigua reportedly escaped major damage, with no loss of life, but more than 90% of structures on Barbuda were damaged or destroyed, the prime minister says

St Martin

• Population: 75,000

• Key facts: tourist destination celebrated for its beaches; divided between France, which calls its section Saint Martin, and the Netherlands, which calls its part Sint-Maarten

• Hurricane report: serious damage to buildings, flooding, power cuts

St Barts (Saint Barthélemy)

• Population: 9,200

• Key facts: luxury tourist destination

• Hurricane report: serious damage to buildings, flooding, power cuts

Turks and Caicos

• Population: 31,500

• Key facts: enjoys one of the more dynamic economies in the region thanks to upmarket tourism, offshore finance and fishing

• Hurricane report: the low-lying region is at risk of a storm surge with destructive waves up to 6m (20ft) higher than usual possible

British Virgin Islands

• Population: 20,600

• Key facts: more than 40 islands and islets

• Hurricane report: Irma is passing over the northern islands

Puerto Rico

• Population: 3.7 million

• Key facts: a tourist destination but plagued by debt, poverty and high unemployment

• Hurricane report: Irma expected to pass close by

Dominican Republic

• Population: 10.2 million

• Key facts: major tourist destination, shares island of Hispaniola with Haiti

• Hurricane report: Irma expected to pass close by

Some islands in the region are almost at sea level and any significant storm surges would be potentially deadly, the BBC's Will Grant reports from Havana.

Antigua and Barbuda Prime Minister Gaston Browne announced the huge destruction on Barbuda, population 1,600, in a satellite phone call to local broadcaster ABS TV and radio.

However, Antigua, population 80,000, escaped major damage, with no loss of life, he said earlier.

US President Donald Trump has declared a state of emergency for Florida, Puerto Rico and the US Virgin Islands, mobilising federal disaster relief efforts.

In Florida's Key West, visitors will be required to leave on Wednesday morning, with residents due to follow in the evening.

"Watching Hurricane closely," Mr Trump tweeted on Wednesday. "My team, which has done, and is doing, such a good job in Texas, is already in Florida. No rest for the weary!"

Parts of Texas and Louisiana are dealing with the damage done by Hurricane Harvey in late August. But it is not yet clear what impact Hurricane Irma might have on the US mainland.

The US House of Representatives on Wednesday approved roughly $8bn (£6.1bn) in initial emergency aid for states affected by Harvey. The measure will now go to the Senate.

• Texas recovery from Harvey 'could cost $180bn'

• Uninsured and anxious, victims return home

• How hard has Harvey hit the local economy?

A third storm further out in the Atlantic behind Irma swelled to category one hurricane strength on Wednesday, the US National Hurricane Center confirmed. Hurricane Jose has a maximum sustained wind speed of 75km/h.

Seeing multiple storms developing in the same area of the Atlantic in close succession is not uncommon.

Rarer though is the strength of the hurricanes, with Harvey making landfall in the US as a category four.

There have never been two category four storms making landfall on the US mainland during the same season, since records began.