An Antiguan journalist, based in Texas, is reporting power cuts in the Antiguan capital.

And the Trinidad and Tobago Weather Center says there is flash flooding in Martinique and heavy rain in parts of Trinidad.

Aid agencies are springing into action as Maria tears a path across the Caribbean.

Unicef's Spanish committee tweets: "We are closely following the hurricane #Maria that is moving along a similar path to the violent #Irma. We are ready to help the children."

A picture has emerged online allegedly showing Dominica in 1979, after Hurricane David wreaked havoc there.

That deadly storm destroyed or damaged 80% of homes on the island, with savage winds eroding the coastline and damaging coastal roads.

The country's Prime Minister Roosevelt Skerrit has said he fears the island will awake to fatalities this time around too.

He wrote on Facebook three hours ago: "Come tomorrow morning we will hit the road, as soon as the all clear is given, in search of the injured and those trapped in the rubble."

BBC Radio 5 live

Myles Allen, a professor of geosystem science at the University of Oxford, explains why the Caribbean seems so vulnerable.

"In the Caribbean there's a lot of energy available. The sea surface temperatures are warm and able to fuel these hurricanes, and also the atmosphere is relatively still and that allows these hurricanes to develop.

"Certain factors do load the dice in favour of hurricanes developing."

The island of Dominica had more than 6 inches of rain in 24 hours as Hurricane Maria passed over, according to local forecasters.

• The Caribbean island of Dominica has suffered "widespread damage". "We have lost all that money can buy," the island's prime minister said in a series of live posts, as the roof of his own home was blown off.
• After hitting Dominica, the storm was downgraded from a category five - the highest level - to a four, with winds of up to 250km/h (155mph).
• The US territory of Puerto Rico expects Maria to make landfall as at least a category three storm later on Tuesday. It escaped the worst of Hurricane Irma and has been an important hub for getting relief to islands more badly affected.
• President Donald Trump declared a state of emergency for the US Virgin Islands on Monday.
• On the British Virgin Islands more than 1,300 troops are in place, with reinforcements on their way.
• Maria is taking aim at vulnerable islands in the region which are still coping with the devastation caused by Irma earlier this month.

Trinidad and Tobago weather center reports high winds and flash flooding in south Trinidad, thanks to an "intense outer band" of the hurricane.

Maria is reported to be over the south of Guadeloupe right now.

There are hurricane warnings in place for:

• the Caribbean islands of St Kitts and Nevis and Montserrat
• the US Virgin Islands
• the British Virgin Islands
• and Puerto Rico

Hurricane watches are also in place for:

• St Martin, the part French-part Dutch Caribbean island
• the Dutch islands of Saba and St Eustatius in the Caribbean
• the British territory of Anguilla, also in the Caribbean

Hurricane Maria is over the south of Guadeloupe right now. People there are being urged again to stay inside.

One Twitter user, Caroline Green, says her brother-in-law is sheltering under a bed in his hotel room on the island.

Image source, AFP/Getty

Maria is expected to be Puerto Rico's most powerful hurricane for 85 years, since a category 4 storm swept through in 1932.

Governor Ricardo Rossello told CNN: "We've made preparations... we've focused on really the only thing that matters right now, which is making sure people are safe. We have 500 shelters, (we're) moving people to those shelters and hopefully weathering the storm so we can rebuild Puerto Rico."

Mr Rossello said the island is braced for about two-and-a-half days of tropical storm force winds, and sustained hurricane winds for "the better part of a day".

Puerto Rico narrowly avoided a direct hit from Hurricane Irma just two weeks ago.

Unsurprisingly, the latest advice, external from the UK Foreign and Commonwealth Office is not to travel to the British Virgin Islands.

It is warning residents to identify shelter "immediately" and be ready to take cover when the hurricane approaches.

Local authorities have imposed a curfew which will continue until the all clear is given, the FCO said.

Officials are also warning against all but essential travel to Montserrat and Anguilla, other British territories.

This radar map, tweeted by atmospheric science student Philippe Papin, shows how Dominica's mountainous terrain shaped the path of Hurricane Maria.

Violent winds are already battering the French territory of Guadeloupe, home to 465,000, which is next in Maria's path. Its people are being warned to stay inside and not to go out under any circumstances.

Sir Richard Branson has launched an emergency appeal for funds to help the British Virgin Islands.

"These hurricanes are causing unimaginable destruction," he writes. "In the BVI infrastructure has collapsed".

The airline mogul is calling for a "long-term Marshall Plan" for the battered BVI, and for the Caribbean to be "reconstructed and rejuvenated with clean energy and new jobs".

Maria is now tracking towards the Virgin Islands. Relief workers there are racing to secure debris still strewn across the islands after Hurricane Irma, which could worsen the damage from the new storm if it is picked up by high winds.

The British territory of Anguilla, to the east of Puerto Rico, was also badly damaged by Hurricane Irma earlier this month.

Alison Strand, who lives there, said people were very concerned about the debris from the last storm.

People are trying to tie down what they can, trying to get their houses sealed as best they can," she said.

"We're not scheduled to get the eye of the storm, we think that we'll get the tail which brings with it a lot of rain and a high surge tide as well."

There is never a good time for a hurricane of this strength to hit a small Caribbean nation such as Dominica, writes the BBC's Sean Fanning, who has just returned from the island, where his relatives live.

But the timing of this storm is doubly heart-wrenching as parts of Dominica are still recovering from Tropical Storm Erika, which hit in 2015.

The rugged mountainous beauty which makes this rainforest-covered island a Unesco world heritage site is also its achilles heel when heavy rainfall strikes.

Erika brought mudslides and flooding which left at least 31 people dead. Normally tranquil mountain streams and rivers turned into raging torrents which swept away bridges cutting off some villages in the Atlantic-facing south-east of Dominica for weeks.

A drive last week from the capital, Roseau, over the mountainous interior took longer than expected as extensive road repairs and bridge-building continue.

The US National Hurricane Center says Maria is the most powerful storm ever to make landfall in Dominica. The hurricane's intensity may vary over the next day or two, but it's expected to remain a category 4 or 5 storm.