The storm was temporarily downgraded to a category four but returned to five within a few of hours
Hurricane Maria has ripped through the Caribbean island nation of Dominica.
Dominica's Prime Minister Roosevelt Skerrit posted on Facebook that he could hear the sound of "merciless winds" ripping roofs from houses.
He said 160mph winds and hours of rain had caused "mind-boggling, widespread devastation" across the nation.
"Initial reports are of widespread devastation," he said. "So far we have lost all what money can buy and replace."
"My greatest fear for the morning is that we will wake to news of serious physical injury and possible deaths as a result of likely landslides triggered by persistent rains."
He urged other countries to send aid - including helicopters to survey the island from the air in a search for people trapped under rubble.
"We will need help, my friend," he wrote. "We will need help of all kinds."
With maximum sustained winds of 160mph, the US National Hurricane Centre says Maria was a category five storm when it hit Dominica in the early hours of Tuesday.
After hours spent pounding Dominica, Maria was temporarily downgraded to a category four storm but returned to five - the strongest on the scale - within a couple of hours. Experts cautioned that fluctuations in intensity should be expected.
Officials in nearby Guadeloupe warned of heavy flooding.
Forecasters say the storm looks set to target Puerto Rico and the island of Hispaniola, shared by the Dominican Republic and Haiti.
"You have to evacuate. Otherwise, you're going to die," Puerto Rico's public safety commissioner urged on Monday.
Up to 51cm (20 inches) of rain could also drench the British and US Virgin Islands on Wednesday night.
Cat Clayton, who owns a hotel on the British Virgin Islands, told Sky News that it was now too late to escape - and that she was preparing to weather the storm from Tortola.
"It can't get much worse that what it is," she said. "We have to pull together as a community, as a family and just hunker down and get on with our days, get ready and prepared as we possibly can."
Some 80% of all Tortola's buildings were damaged or totally destroyed by Hurricane Irma.
Its 185mph winds stripped trees and power lines, scattered yachts, shipping containers and cars in all directions, and tore entire homes to pieces.
The debris it left is now scattered across the island, ready to be picked up again by Hurricane Maria.
Brigadier John Ridge, second in command of the Joint Task Force of troops helping the islanders to recover, said: "It kind of does not matter which way the hurricane goes, it is bad.
"They are either going to get the wind, which will pick up all the debris that is lying around...or they get a huge amount of rain, which is also bad because of the blockages in the drainage channels.
"Whatever happens, it doesn't look good, sadly."