Hurricane Maria destroyed buildings and knocked out power across Puerto Rico before flooding parts of the Dominican Republic and then regaining some of its strength as it approached the Turks and Caicos Islands and southeastern Bahamas late on Thursday.

The second major hurricane to rage through the Caribbean this month, Maria has killed at least 32 people and devastated several small islands, including St. Croix in the U.S. Virgin Islands and Dominica. At least 15 people were killed in Puerto Rico, the island's El Nuevo Dia newspaper reported.

Among those were eight people who drowned in Toa Baja, about 32 kilometres west of San Juan, Mayor Bernardo Mirquez told the newspaper, adding the names of those who died have not been released and the causes of death had to be confirmed through autopsies.

More than 4,000 people had been rescued from flooded areas of Toa Baja, the mayor was quoted as saying.

3 sisters killed in mudslide

Three elderly sisters were killed by a mudslide on Wednesday in the mountainous central municipality of Utuado, El Nuevo Dia said, citing relatives and the mayor of Utuado.

Maria, headed toward the Turks and Caicos islands, is now a Category 3 hurricane on the five-step Saffir-Simpson scale, with sustained winds of up to 205 km/h. It was 110 kilometres east-southeast of Grand Turk Island as of 11 p.m. ET, the U.S. National Hurricane Center said.

Puerto Rico Hurricane Maria

Irma Torres Rodriguez tries to stay calm after losing a portion of her roof to the fury of Hurricane Maria in Puerto Rico. (Carlos Gusti/Associated Press)

Maria was expected to bring as much as 102 centimetres of rain to Puerto Rico and 20 to 40 centimetres to the Turks and Caicos, which could cause flash floods and mudslides, the NHC said.

Maria's strength was not expected to change during the next few days, the centre said.

Strongest hurricane in 90 years

The storm looked unlikely to hit the continental United States but its storm swells will reach the U.S. southeastern coast from Friday, the NHC said.

Officials in Puerto Rico were assessing the damage after Maria slammed the island on Wednesday with winds of up to 250 km/h. Ranked a Category 4 storm when it made landfall, it was the strongest hurricane to hit the island in nearly 90 years.

'They're not gonna find home … everything will be lost'0:56

U.S. President Donald Trump told reporters the island had been "totally obliterated" and that he planned to visit.

Puerto Rico Gov. Ricardo Rossello imposed a dusk-to-dawn curfew through Saturday on the island of 3.4 million people.

"If it is not an emergency situation, people should remain in their homes or shelters," he was quoted as saying by El Nuevo Dia.

95% of roofs damaged

Maria struck Dominica as a Category 5 storm on Monday night, damaging about 95 percent of the roofs on the island, the UN Office for the Co-ordination of Humanitarian Affairs said.

At least 14 people died, CNN quoted Charles Jong, a spokesperson for the Dominica prime minister's office, as saying. Two people were killed in the French territory of Guadeloupe and one person on the U.S. Virgin Islands.

hurricane maria

A car is submerged in a flooded street in Santurce, in San Juan, on Thursday. (Hector Retamal/AFP/Getty Images)

Utility crews from the U.S. mainland were headed to Puerto Rico to help try to restore the battered power grid and the U.S. military sent ground forces and aircraft to assist with search and rescue.

More than 95 percent of wireless cell sites were not working on Thursday afternoon on the island, the U.S. Federal Communications Commission said.

75% of cell sites out of service

In the U.S. Virgin Islands, more than three-quarters of cell sites are out of service.

Puerto Rico was already facing the largest municipal debt crisis in U.S. history, and a team of judges overseeing its bankruptcy has advised involved parties to put legal proceedings on hold indefinitely as the island recovers, according to a source familiar with the proceedings.

Puerto Rico Hurricane Maria

Power lines are down in Humacao, Puerto Rico, after the hurricane. (Carlos Giusti/Associated Press)

In the historic heart of the island's capital San Juan, which has a fort and buildings from the Spanish colonial era, the storm left a litter of wreckage. Roads were blocked by downed foliage and firefighters and rescue officials wielded chain saws to cut through the debris.

San Juan airport reopened for military and relief flights on Thursday, with plans for a limited resumption of commercial flights on Friday. With electricity and communications knocked out across the island, workdays evaporated and people busied themselves with securing food, checking on their battered homes and collecting rain water.

'The worst is behind us'

Maria passed close by the U.S. Virgin Island of St. Croix, home to about 55,000 people, early on Wednesday as a rare and ferocious Category 5 storm, knocking out electricity and most mobile phone service.

"The worst is behind us," Virgin Islands Governor Kenneth Mapp told reporters on Thursday. "Now is [the] time to march forward and build a better community, a better territory."

The government has imposed a 24-hour curfew until further notice. About 600 people throughout the U.S. Virgin Islands are in emergency shelters and many parts are without power, Mapp said.

"It's going to be a long road to recovery," Mapp said. "It ain't going to happen in a week or two and it definitely ain't going to happen in a few months."

Maria hit about two weeks after Hurricane Irma pounded two other U.S. Virgin Islands: St. Thomas and St. John.

Irma, one of the most powerful Atlantic storms on record, killed at least 84 people in the Caribbean and the United States. It followed Harvey, which killed more than 80 people when it hit Texas in late August and caused historic flooding in Houston.

More than two months remain in the Atlantic hurricane season, which runs from June 1 to Nov. 30.