ROSEAU, Dominica -- Hurricane Maria swept over the small island of Dominica with catastrophic winds overnight, starting a charge into the eastern Caribbean that threatens islands already devastated by Hurricane Irma and holding the possibility of a direct hit on Puerto Rico.

Fierce winds and driving rain lashed mountainous Dominica for hours as Maria caused flooding and tore roofs from homes as an extremely dangerous Category 5 storm. A police official on the island, Inspector Pellam Jno Baptiste, said late Monday there were no immediate reports of casualties but it was too dangerous for officers to do a full assessment as the storm raged outside.

"Where we are, we can't move," he said in a brief phone interview while hunkered down against the region's second Category 5 hurricane this month.

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By early Tuesday, Maria had weakened slightly to a still major Category 4 storm after pounding the small Caribbean island nation. It then regained Category 5 strength. Forecasters cautioned that fluctuations in intensity were to be expected.

Forecasters consider a Category 5 hurricane as major, extremely dangerous and capable of catastrophic winds.

On the forecast track, the eye of Maria will move over the northeastern Caribbean Sea Tuesday and approach the Virgin Islands and Puerto Rico Tuesday night and Wednesday, the U.S. National Hurricane Center said.

A map shows the probable path for Hurricane Maria as of 8 a.m. ET on Sept. 19, 2017. The M stands for "major hurricane." The red areas represent hurricane warnings. The blue areas represent tropical storm warnings. The pink areas represent hurricane watches. The yellow areas represent tropical storm watches. National Hurricane Center

Dominica Prime Minister Roosevelt Skerrit earlier captured the fury of Maria as it made landfall. "The winds are merciless! We shall survive by the grace of God," Skerrit wrote at the start of a series of increasingly harrowing posts on Facebook.

A few minutes later, he messaged he could hear the sound of galvanized steel roofs tearing off houses on the small rugged island.

He then wrote that he thought his home had been damaged. And three words: "Rough! Rough! Rough!"

A half hour later, he said: "My roof is gone. I am at the complete mercy of the hurricane. House is flooding." Seven minutes later, he posted that he had been rescued.

Skeritt said there were initial reports of "widespread devastation" on the small island, adding that his "greatest fear" is that the people of Dominica will wake to news of "serious physical injury and possible deaths."

The French island of Martinique escaped Hurricane Maria largely unscathed but a communications blackout with Guadeloupe meant it would be several more hours before damage there could be assessed, a senior French Civil Protection official told the Reuters news service Tuesday.

Authorities in the U.S. territory of Puerto Rico warned that people in wooden or flimsy homes should find safe shelter before the storm's expected arrival.

"You have to evacuate. Otherwise, you're going to die," said Hector Pesquera, the island's public safety commissioner. "I don't know how to make this any clearer."

Navy MH-60S Sea Hawk helicopter lifts off from the flight deck of the USS Kearsarge as U.S. military continues to evacuate from U.S. Virgin Islands in advance of Hurricane Maria on September 18, 2017 JONATHAN DRAKE / REUTERS

Puerto Rico imposed a rationing of basic supplies Monday, including water and baby formula. Officials said the rationing was necessary to ensure everyone has access to basic items such as batteries, milk, canned foods, flashlights and other supplies. It didn't apply to gasoline or other fuels.

Maria had maximum sustained winds of 160 mph late Monday as it slammed into Dominica as a Category 5 storm, its eye passing over the island before conditions began easing, then rebounding.

At 8 a.m., its top sustained winds remained near 160 mph and its eye was about 85 miles west of Guadeloupe and about 170 miles southeast of St. Croix. The major hurricane was moving to the west-northwest at 9 mph.

Before the latest fluctuation in intensity, forecasters had warned Maria would likely intensify over the next 24 hours or longer, noting its eye had shrunk to a compact 10 miles across and warning, "Maria is developing the dreaded pinhole eye."

That generally means an extremely strong hurricane will get even mightier, said Brian McNoldy, a hurricane researcher at the University of Miami. He said it just like when a spinning ice skater brings in their arms and rotates faster.

"You just don't see those in weaker hurricanes," he said.

Hurricane warnings were posted for the U.S. and British Virgin Islands, Puerto Rico, Dominica, St. Kitts, Nevis and Montserrat. A tropical storm warning was issued for Antigua and Barbuda, Saba, St. Eustatius, St. Maarten, St. Lucia and Anguilla.

Forecasters said storm surge could raise water levels by 6 to 9 feet near the storm's center. The storm was predicted to bring 10 to 15 inches of rain across the islands, with more in isolated areas.

The latest forecast track would carry it about 22 miles south of St. Croix in the U.S. Virgin Islands late Tuesday and early Wednesday, territorial Gov. Kenneth Mapp said.

"We are going to have a very, very long night," Mapp said as he urged people in the territory to finish any preparations.

St. Thomas and St. John are still stunned from a direct hit by Hurricane Irma, which did extensive damage and caused four deaths on the two islands.

Barry University said it chartered a private plane to carry students and staff from its St. Croix facility to Florida in preparation for Maria. It said 72 people connected to the Barry's Physician Assistant Program and a few pets were on Monday's evacuation flight.

In neighboring Puerto Rico, nearly 70,000 people were still without power following their earlier brush with Irma and nearly 200 remained in shelters as Maria approached.

Gov. Ricardo Rossello said Puerto Rico had 500 shelters capable of taking in up to 133,000 people in a worst-case scenario. He also said the Federal Emergency Management Agency was ready to bring drinking water and help restore power immediately after the storm, which could hit as a Category 5 hurricane.

"That is catastrophic in every way," said Roberto Garcia with the National Weather Service in San Juan. "People have to act, and they have to act now. They can no longer wait for a miracle."

To the north, Hurricane Jose stirred up dangerous surf and rip currents along the U.S. East Coast, though forecasters said the storm was unlikely to make landfall. Big waves caused by the storm swept five people off a coastal jetty in Rhode Island and they were hospitalized after being rescued.

A tropical storm warning was posted for coastal areas in Rhode Island and Massachusetts, and tropical storm watches were up for parts of New York's Long Island and Connecticut. Jose's center was about 365 miles south of Nantucket, Massachusetts, early Tuesday and moving north at 9 mph. The storm had maximum sustained winds of 75 mph.