A second powerful storm in as many weeks was bearing down on a string of battered Caribbean islands, with forecasters saying Maria would strengthen rapidly into a major hurricane as it ripped into the Leeward Islands on Monday night.
Maria's strength was building as it approached the Lesser Antilles, the US National Hurricane Centre said, estimating its winds near 145kph.
"Maria is expected to become a major hurricane as it moves through the Leeward Islands," the forecaster said, marked by "rapid strengthening" during the next 48 hours.
Maria is approaching the eastern Caribbean less than two weeks after Irma hammered the region before overrunning Florida.
That storm, one of the most powerful ever recorded in the Atlantic with winds up to 298kph, killed at least 84 people, more than half of them in the Caribbean.
As of 0600 GMT Monday, the centre of the storm was about 145km north-northeast of Barbados and about 270km east-southeast of the Leeward island of Dominica, moving to the west-northwest at about 20kph.
Hurricane conditions were expected for Guadalupe, Dominica, Martinique and St. Kitts, Nevis and Montserrat, and the hurricane centre warned Puerto Rico to monitor the storm.
The British Virgin Islands and St Martin, which was devastated by Hurricane Irma, were under a hurricane watch, as were the US Virgin Islands and Anguilla.
More than 1,700 residents of Barbuda, where Irma damaged nearly every building, braced for Maria on neighbouring Antigua, now under a tropical storm watch, said Ronald Sanders, the country's ambassador to the United States.
Puerto Rico has already begun preparations for Maria, which by Tuesday was expected to unleash powerful winds on the US territory, already dealing with a weakened economy and fragile power grid.
The hurricane centre also issued a tropical storm watch for portions of the US mid-Atlantic and New England coast by Tuesday as a second hurricane, Jose, moved slowly north from its position in the Atlantic Ocean about 510km southeast of Cape Hatteras, North Carolina.
The eye of Jose, with top sustained winds of 145km per hour, should remain off the US East Coast, the NHS said.
Even so, by Tuesday it could bring tropical storm conditions from Fenwick Island, Delaware, to Sandy Hook, New Jersey, and from East Rockaway Inlet on New York's Long Island to the Massachusetts island of Nantucket.
Up to 13cm of rain could fall over parts of the area, and the storm could bring dangerous surf and rip currents as well.
