A dangerous and extremely powerful Hurricane Beryl made landfall on Monday on the Caribbean island of Carriacou after becoming the earliest storm of Category 4 strength to form in the Atlantic, fuelled by record warm waters.

Winds up to 150 mph, just shy of a Category 5 storm, blew off roofs, uprooted trees and caused other damage on Carriacou, one of the islands of Grenada, and elsewhere in the southeast Caribbean.

“This is an extremely dangerous and life-threatening situation,” the National Hurricane Centre said.

Hurricane warnings were in effect for Barbados, Grenada, Tobago and St Vincent and the Grenadines as thousands of people hunkered down in homes and shelters.

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

NBC Radio in St Vincent and the Grenadines said it received reports of roofs being torn off churches and schools as communications began collapsing across the southeast Caribbean.

In nearby Grenada, officials received “reports of devastation” from Carriacou and surrounding islands, said Terence Walters, Grenada’s national disaster co-ordinator. Prime minister Dickon Mitchell said he would travel to Carriacou as soon as it is safe, noting that there has been an “extensive” storm surge.

Grenada officials had to evacuate patients to a lower floor after a hospital roof was damaged, he said.

“There is the likelihood of even greater damage,” he told reporters. “We have no choice but to continue to pray.”

Later on Monday morning, Beryl was about 30 miles (50km) north of the island of Grenada, moving west-northwest at 20 mph (31 kph).

In Barbados, officials received more than a dozen reports of roof damage, fallen trees and downed electric posts across the island, said Kerry Hinds, emergency management director. Wilfred Abrahams, minister of home affairs and information, said drones — which are faster than crews fanning across the island — would assess the damage once Beryl passes.

A tropical storm warning was in effect for St Lucia, Martinique and Trinidad. A tropical storm watch was issued for Haiti’s entire southern coast, and from Punta Palenque in the Dominican Republic west to the border with Haiti. A hurricane watch was issued for Jamaica.

Forecasters warned of a life-threatening storm surge of up to nine feet (three metres) in areas where Beryl made landfall, with three to six inches (7.6 to 15 cm) of rain for Barbados and nearby islands and possibly 10 inches in some areas (25 cm), especially in Grenada and the Grenadines.

The storm was expected to weaken slightly over the Caribbean Sea on a path that would take it just south of Jamaica and later toward Mexico’s Yucatan Peninsula as a Category 1.

“Beryl is forecast to remain a significant hurricane during its entire trek across the Caribbean region,” the National Hurricane Centre said.

Officials in some southeast Caribbean islands announced controlled power outages and warned of water cuts ahead of the storm, as well as landslides and flash floods. Schools, airports and government offices shuttered.

Hours before the storm, Barbadian Michael Beckles said he still feared the worst for his island.

“As prepared as we can try to be, there are a lot of things that we can’t control,” he said. “There are a lot of houses that are not ready for a storm like this.”

Beryl strengthened from a tropical depression to a major hurricane in just 42 hours — a feat accomplished only six other times in Atlantic hurricane history, and with September 1 as the earliest date, according to hurricane expert Sam Lillo.