Nearly two-thirds of homes in Florida are without power
Four storm-related deaths have been reported so far in Florida
The weakening storm is crossing into Georgia
At least 37 people were killed as Irma rolled across the Caribbean
Irma has damaged more than 90% of buildings on Barbuda, the Prime Minister of Antigua and Barbuda, Gaston Browne, says.
But the exact extent of the damage and possible casualties is still unclear because communication has been lost with the island.
Storm Jose has strengthened to become a hurricane, with additional strengthening expected, the US National Hurricane Center says, external, warning that it could be near major hurricane strength on Friday.
The storm is now far from land and well east of Hurricane Irma.
Jose has sustained winds of up to 120km/h (75mph). There are no coastal watches or warnings in effect.
Image source, EPA/NOAAStorm Katia has strengthened to become a hurricane in the Gulf of Mexico, the US National Hurricane Center says, with sustained winds of up to 120km/h (75mph).
A hurricane watch is in effect for the coast of the state of Veracruz.
Image source, ReutersSpeaking in North Dakota, US President Donald Trump says the Federal Emergency Management Agency (Fema) is responding to Hurricane Irma.
He says Fema crews have already been sent to Florida, Puerto Rico and the Virgin Islands of the US. A state of emergency had already been declared in those areas.
Mr Trump also warns that Irma could be the largest hurricane in the recorded history.
BBC's Laura Bicker says the effects of Hurricane Irma are already being felt in Puerto Rico
Storm Jose has strengthened to become a hurricane, with sustained winds of up to 120km/h (75mph) and is heading for the Caribbean, the US National Hurricane Center says.
The White House has announced that President Donald Trump will donate $1m (£770,000) towards disaster relief in Texas after Hurricane Harvey struck there last month.
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On Wednesday, Houston Mayor Sylvester Turner asked residents to be patient as the city returns to normal.
"I think every day things will get better, I think every week things will get better," the mayor said at a press conference, "but we had to get back to work".
The US space agency Nasa has posted dramatic footage from the International Space Station of Hurricane Irma's landfall earlier on Wednesday.
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US officials in Puerto Rico say that wind speeds have already reached over 110mph in the Virgin Islands.
Social media videos show palm trees whipping from side to side, as rain pummels glass windows.
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Hurricane Irma: Last-minute preparations in Puerto Rico
More from the French overseas territories minister (see entry 13 minutes ago)
Annick Girardin stresses the urgency to bring relief and - if necessary - evacuate local residents from the islands.
But she says the authorities want first of all to properly assess the situation as the communications with the region are just beginning to return.
She was speaking to reporters on her way to the affected region.
Image source, AFP/Getty ImagesSubmerged cars on the French overseas island of Saint-Martin
Image source, ReutersA man removes debris that damaged a car in San Juan, Puerto Rico
Image source, Royal Netherlands NavyFallen trees on the island of Sint Eustatius, part of the Caribbean Netherlands
France's overseas minister says two people have been killed and another two seriously injured in the French Caribbean territories.
Hurricane Irma may be breaking records, but it's not the first hurricane to approach (or even surpass) wind speeds of 185mph/ 295km/h.
In 1988, Hurricane Gilbert left 316 people dead on Jamaica and in the Gulf of Mexico.
In 2015, Hurricane Patricia broke all records by reaching wind speeds of 215mph/ 345km/h, however it had weakened significantly by the time it reached land.
Read about how Irma compares to other category five hurricanes.
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More from French President Emmanuel Macron.
Speaking in Paris, he said: "At this moment, it is too early to put the death toll.
"But I can already say that the impact will be harsh and cruel, and we'll be mourning victims."
Image source, AFP/Getty ImagesFrench President Emmanuel Macron says there will be deaths in France's Caribbean territories after the passage of Hurricane Irma.
But he told French media it was too early to say how many victims there could be.
Significant damage had been done to the islands, he added.
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Hurricane Irma is being slowly trailed by Tropical Storm Jose, which is moving very slowly in the Atlantic Ocean.
Irma has already plowed through the island of St Martin, the Virgin Islands, and other small islands in the eastern Caribbean.
It is expected to pass about 30 miles to the north of Puerto Rico's capital in the next several hours.
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Winds are also rapidly picking up in San Juan, Puerto Rico, where the BBC broadcast team is reporting.
The latest projections say the hurricane will pass 30 miles north of San Juan between 18:00 - 20:00 local time.
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The US National Hurricane Centre released a fresh advisory, external at 1400 AST (1800 GMT).
Hurricane Irma is about 20 miles (35km) east-north-east of St Thomas in the Virgin Islands, and about 90 miles (150km) east of San Juan, Puerto Rico.
The storm has not slowed down.
But as it moves, the local government in Sint Maarten has lifted the Hurricane warning there, and it has also been lifted in Anguilla.
The governor in the US territory of Puerto Rico has asked the Department of Defense to activate the National Guard as Irma closes in on the island.
Ricardo Rosselló asked for the troops to help in recovery efforts after the storm passes, his office said.
In a statement, the governor said citizens should already be in a suitable shelter.
The latest forecast predicts the hurricane will pass just north of San Juan later this evening.