Hurricane Beryl roared through open waters on Tuesday as a powerful Category four storm heading towards Jamaica after earlier crossing islands in the south-east Caribbean, killing at least six people.

A hurricane warning was in effect for Jamaica, Grand Cayman, Little Cayman, and Cayman Brac.

Beryl was losing intensity but was still forecast to be near major-hurricane strength when it passes near or over Jamaica early on Wednesday, near the Cayman Islands on Thursday and into Mexico’s Yucatan Peninsula on Friday, according to the National Hurricane Centre.

A hurricane watch was in effect for Haiti’s southern coast and the Yucatan’s east coast. Belize issued a tropical storm watch stretching south from its border with Mexico to Belize City.

Late on Monday, Beryl became the earliest storm to develop into a Category five hurricane in the Atlantic and peaked at winds of 165mph (270kph) on Tuesday before weakening to a still-destructive Category four.

Early on Wednesday, the storm was about 250 miles (400 kilometres) east-southeast of Kingston, Jamaica. It had top winds of 145mph (230kph) and was moving west-northwest at 22mph (35kph), the centre said.

Beryl was expected to bring life-threatening winds and storm surge to Jamaica, where officials warned residents in flood-prone areas to prepare for evacuation.

“I am encouraging all Jamaicans to take the hurricane as a serious threat,” Prime Minister Andrew Holness said in a public address Tuesday. “It is, however, not a time to panic.”

In Miami, National Hurricane Centre director Michael Brennan said Jamaica appears to be in the direct path of Beryl.

“We are most concerned about Jamaica, where we are expecting the core of a major hurricane to pass near or over the island,” he said in an online briefing. “You want to be in a safe place where you can ride out the storm by nightfall (Tuesday). Be prepared to stay in that location through Wednesday.”

Storm surge of 6-9ft (1.8-2.7m) above typical tide levels are likely in Jamaica, as well as heavy rainfall.

“This is a big hazard in the Caribbean, especially with the mountainous islands,” Mr Brennan said. “This could cause life-threatening flash floods and mudslides in some of these areas.”

A tropical storm warning was in place for the entire southern coast of Hispaniola, an island shared by Haiti and the Dominican Republic.

As the storm barrelled through the Caribbean Sea, rescue crews in south-eastern islands fanned out to determine the extent of the damage Beryl inflicted on Carriacou, an island in Grenada.

Three people were reported killed in Grenada and Carriacou and another in St Vincent and the Grenadines, officials said.

Two other deaths were reported in northern Venezuela, where five people are missing, officials said. Some 25,000 people in that area also were affected by heavy rainfall from Beryl.

One fatality in Grenada occurred after a tree fell on a house, Kerryne James, the environment minister, told The Associated Press.

She said Carriacou and Petit Martinique sustained the greatest damage, with scores of homes and businesses flattened in Carriacou.

“The situation is grim,” Grenadian Prime Minister Dickon Mitchell told a news conference on Tuesday. “There is no power, and there is almost complete destruction of homes and buildings on the island. The roads are not passable, and in many instances, they are cut off because of the large quantity of debris strewn all over the streets.”

Mr Mitchell added: “The possibility that there may be more fatalities remains a grim reality as movement is still highly restricted.”

Meanwhile, Ralph Gonsalves, prime minister of St Vincent and the Grenadines, promised to rebuild the archipelago. He noted that 90% of homes on Union Island were destroyed, and that “similar levels of devastation” were expected on the islands of Myreau and Canouan.

Several people evacuated Union Island via ferry and arrived at the Kingstown Ferry Terminal in St Vincent and the Grenadines on Tuesday.

Sharon DeRoche, one of the evacuees, said Union Island is in a terrible state. She bore the hurricane in her bathroom before she fled.

“It was a hard four hours battling with six of us in that little area,” she said.

The last strong hurricane to hit the southeast Caribbean was Hurricane Ivan 20 years ago, which killed dozens of people in Grenada.

Grenadian resident Roy O’Neale, 77, lost his home to Ivan and built back stronger. His current home sustained minimal damage from Beryl.

“I felt the wind whistling, and then for about two hours straight, it was really, really terrifying at times,” he said by phone. “Branches of trees were flying all over the place.”

Hundreds of people hunkered in shelters across the south-east Caribbean, including 50 adults and 20 children who huddled inside a school in Grenada.

“Maybe some of them thought they could have survived in their homes, but when they realised the severity of it … they came for cover,” said Urban Mason, a retired teacher who served as the shelter’s manager. “People tend to be complacent.”

One of the homes that Beryl damaged belongs to the parents of UN climate change executive secretary Simon Stiell, who is from Carriacou. The storm also destroyed the home of his late grandmother.

In a statement, Mr Stiell said that the climate crisis is worsening, faster than expected.

“Whether in my homeland of Carriacou … hammered by Hurricane Beryl, or in the heatwaves and floods crippling communities in some of the world’s largest economies, it’s clear that the climate crisis is pushing disasters to record-breaking new levels of destruction,” he said.