The US National Oceanic and Atmospheric Administration tweets...

The BBC's Jeremy Cooke has the latest from Tortola, in the British Virgin Islands, where residents are bracing for a second "catastrophic" hurricane in as many weeks.

Preparations are underway in Puerto Rico, which is expected to be hit later on Tuesday by Maria.

Mark Moriarty, a tech entrepreneur living in the capital, San Juan, sent this picture of empty shelves in a supermarket as people rushed to buy supplies.

Puerto Rico Governor Ricardo Rosselló told the island's 3.5 million residents to seek shelter.

Image source, Mark Moriarty

In a video update, the US National Hurricane Center said they are "very concerned about a life threatening storm surge" in Puerto Rico and the US Virgin Islands.

They added that "the core of the hurricane is expected to move over Puerto Rico during the day on Wednesday".

Dr Steven Godby, an expert in natural hazards at Nottingham Trent University, tells the BBC that small island nations like Dominica are particularly vulnerable to tropical cyclones, and the impact can be long-lasting.

"Maria is the first major hurricane to strike [in Dominica] since Hurricane David took 40 lives in 1979," he said.

"This is the peak period of the Atlantic hurricane season, which runs from June to November, and we have the right ingredients for hurricane formation at the moment.

"Sea surface temperatures are higher than average, wind shear - which is the change in speed and direction of winds from surface level to high in the atmosphere - is low, and there has not been any major input of dry, dusty air from the Sahara which can impact the development of these storms."

Local media in the French overseas territory of Guadeloupe are sharing video and images showing flooding on the island.

Maria is currently off the south shores of Guadeloupe, where authorities have told residents to seek shelter and not go out under any circumstances.

Tropical storm warnings have been discontinued in St Lucia and St Vincent and the Grenadines, the US National Hurricane Center says.

The alerts are issued when tropical storm conditions are expected "somewhere within the warning area". The NHC shared its latest 8:00 AST (12:00 GMT) advisory on Twitter:

The French Interior Ministry tweets that the hurricane is moving away from Guadeloupe, but people there are still taking refuge. The first reconnaissance operations will start in a few hours.

In Martinique, it says, "the news is reassuring. No major damage. 50,000 households are without electricity and 10,000 are without water".

"The population must remain at home. The situation remains dangerous," it adds.

Weather experts have been considering what Maria does next.

A meteorological scientist at The Weather Company, based in Boston, tweets:

And NBC News weatherman, in New York, fears Puerto Rico will take the brunt.

• Dominica is the worst-hit territory at present. The Caribbean island's prime minister, who was rescued when the roof of his own home was blown off, says he is dreading waking up to news of serious physical injury and possible deaths from likely landslides.

• Maria jumped from a category three to a vicious category five within just a few hours, taking Dominica by surprise. Warmer sea temperatures are thought to have been a factor in its rapid escalation.

• Life-threatening mudslides, flash floods and storm surges have been predicted by the US National Hurricane Center, which is monitoring the region.

• Maria is currently hammering parts of the French island of Guadeloupe, where residents have been told to seek shelter and not go out under any circumstances.

• Montserrat, a British overseas territory just to its north, is next in Maria's path.

People on the Caribbean islands of St Kitts and Nevis have passed a terrifying night as Maria's fury rushed in.

Their foreign minister, Mark Brantley, told the BBC it was "a very, very traumatic experience for most of us".

More than 1,300 UK troops were deployed to the British overseas territories of Anguilla, Turks and Caicos and the British Virgin Islands for relief efforts following Hurricane Irma.

They are staying put in the region, as an extra military resilience team of 42 servicemen and women is sent to the British Virgin Islands ahead of Maria's arrival.

A French civil protection official tells Reuters news agency that power has been knocked out on Guadeloupe.

No serious damage has been caused in the French Antilles, he adds.

Martinique, a French island south of Dominica, is suffering power cuts but has avoided major damage as the storm skirted its shores.

Flooding, mudslides and power outages have been reported in parts of St Lucia.

Image source, AFP PHOTO / INSTAGRAM / loly_fwi

Officials in Guadeloupe, a French overseas territory in the Leeward Islands, are warning locals to stay sheltered even if the hurricane appears to be easing.

"The phenomenon is still ongoing, it is necessary to remain in a safe place even if lulls appear," said the Prefect of Guadeloupe, Eric Maire.

He said the winds are still blowing strongly, houses and roads are submerged and half of the rain has yet to fall.

Governor of Puerto Rico Ricardo Rossello is urging people there to prepare for Maria in the hours before the vicious storm arrives.

"We have to prepare for an extremely dangerous hurricane. We urge citizens to take action now to ensure their safety," he tweets.

"It is time to take precautions to avoid loss of life. The government continues to work on shelters and contingency plans."

He then retweeted a message from the US TV host Ellen DeGeneres sending good wishes - and urging those facing Maria to take precautions.

BBC World

People on the Caribbean islands of St Kitts and Nevis are taking shelter from Maria's onslaught.

Their foreign minister, Mark Brantley, told the BBC he was apprehensive about what was going to happen.

"Imagine the children, imagine the elderly, imagine those who are sick or hospitalised.

"It is a very, very traumatic experience for most of us.

"Once it's happening, the human element is definitely there.

"There's a tremendous amount of fear and a tremendous amount of just not knowing."

Hurricane Maria has been re-designated as a category five storm, after slipping to category four.

The National Hurricane Center says it is about 205 miles (325km) southeast of St Croix, one of the US Virgin Islands, and is packing wind speeds of 260 km/h (160 mph).