The hurricane had been ranked a Category 4 storm, near the top of the five-step Saffir-Simpson scale, with winds of up to 250km/h, when it rammed into Puerto Rico on Wednesday as the strongest storm to hit the island in nearly 90 years.

Officials in Puerto Rico, home to 3.4 million people, were still assessing the extent of the damage. US President Donald Trump told reporters the storm “totally obliterated” the island.

Puerto Rico Governor Ricardo Rossello said there was one death reported so far, a man struck by a piece of timber hurled by high winds.

“It’s nothing short of a major disaster,” he said in a CNN interview, adding it might take months for the island’s electricity to be completely restored. He imposed a dusk-to-dawn curfew that runs through Saturday.

The storm hit at a time of financial troubles in Puerto Rico, which is facing the largest municipal debt crisis in US history. The team of judges overseeing the Puerto Rican government’s bankruptcy has advised involved parties to put legal proceedings on hold indefinitely as the island recovers from the damage, a source familiar with the legal proceedings said on Thursday.

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 debris.

All of Puerto Rico was under a flash flood warning early on Thursday as the tail end of the storm could bring another 4 to 8 inches (10-20 cm) of rain on Thursday, bringing the storm’s total to 890mm in parts of the island, the NHC said.

The government did not yet have an estimate of how many homes and businesses were destroyed by the storm. But authorities expected to see more people go to shelters on Thursday as they realised how badly their homes were hit, said Pedro Cerame, a spokesman for Rossello.

Thousands went to government shelters before and during the storm.

Maria passed close by the US Virgin Island of St Croix early on Wednesday as a rare and powerful Category 5 storm, knocking out electricity and most mobile phone service across the island, said Keva Muller, a spokeswoman for the emergency operations command on St Thomas. Most radio stations were down and many roads were blocked.

Governor Kenneth Mapp was due to inspect damage by helicopter on Thursday. Just two weeks ago, Hurricane Irma pounded the territory’s northern islands, St Thomas and St John.

As many as 70 per cent of buildings on St Croix, which has a population of about 55,000 people, were damaged, said Holland Redfield, who served six terms in the US Virgin Islands senate.

In the Dominican Republic, winds knocked out power to almost all northern areas, Emergency Operations Centre coordinator Ernesto Pérez told reporters.

Strong winds and rains were lashing the northern shore.

“The tin roofs of some houses were ripped away,” said Juan Carlos Castro Hernandez, assistant district attorney for Puerto Plata, in the northeast of the country.

By Thursday afternoon, Maria was about 135 miles (215km) southeast of Grand Turk island, the NHC said, and it could strengthen somewhat over the coming day or so, the centre said.

It currently looked unlikely to hit the continental United States.

Maria was a rare Category 5 storm when it struck Dominica on Monday night, damaging about 95 per cent of the roofs on the island, the UN Office for the Coordination of Humanitarian Affairs said.

The US and British Virgin Islands were also hit this month by Irma, which ranked as one of the most powerful Atlantic storms on record. It left a trail of destruction in several Caribbean islands and Florida, killing at least 84 people.