• Hurricane Irma, one of the strongest storms ever recorded in the Atlantic, damaged buildings and infrastructure on several islands in the eastern Caribbean on Wednesday, with winds of 185 miles an hour, though no deaths have been reported.
• The Category 5 storm is churning toward Puerto Rico and threatening havoc and widespread destruction on several nearby islands, including St. Kitts and Nevis; the Virgin Islands; and Hispaniola, shared by the Dominican Republic and Haiti. Cuba is also threatened by the hurricane.
• President Trump declared a state of emergency in Florida, Puerto Rico and the United States Virgin Islands. The storm is expected to reach Florida on Sunday morning.
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Roofs were ripped off buildings and homes were flooded on the islands of St. Barthelemy and St. Martin as the storm passed overhead.
The French interior minister, Gérard Collomb, said on Wednesday afternoon after a cabinet meeting in Paris that the authorities did not know of any casualties “for the moment.” But he added that the four “most durable” buildings on St. Martin had been destroyed.
Images from St. Martin show flooded streets and boats tangled in the marina.
President Trump owns a property in St. Martin, Le Château des Palmiers, a walled waterfront estate that is currently up for sale. It is unclear whether that property was damaged.
Power was out on St. Barthélemy and the roofs of many buildings had been blown off, according to a statement from the prefecture on the French island of Guadeloupe, about 40 miles from Antigua and Barbuda.
The situation on St. Martin was similar: There was no power, the fire station was flooded, and local police station no longer had a roof. The island’s administrative offices were also “partially destroyed,” the statement from Guadeloupe said, adding that the staff had taken shelter in a concrete room.
Speaking after the Paris cabinet meeting, Annick Girardin, the minister for France’s overseas territories, said that the authorities were “preparing for the worst” and that communications with the islands were difficult.
By midmorning on Wednesday, the hurricane was “pounding” the island nation of Anguilla, according to the United States National Hurricane Center.
Alex Woolfall, a British public relations consultant, was staying at The Westin St. Marteen resort in St. Martin when the storm made landfall early Wednesday. Before the storm arrived, the hotel had warned guests to take precautions. Mr. Woolfall tweeted updates during the storm before the power eventually went out.
Hurricane Irma was declared one of the strongest storms ever recorded in the Atlantic as it approached the Leeward Islands of the Caribbean, with winds of 185 miles an hour.
There have been storms with comparable winds in the Caribbean and the Gulf of Mexico, where warm waters can fuel especially dangerous hurricanes.
The National Hurricane Center described the storm as “potentially catastrophic,” and said it expected the hurricane to bring “life-threatening wind, storm surge and rainfall hazards to portions of the northern Leeward Islands, including the Virgin Islands and Puerto Rico” on Wednesday.
A new Category 5 storm is bearing down on the Caribbean and could make landfall in Florida this weekend.
In Miami-Dade County, Florida’s most populous, memories of the damage brought in 1992 by Hurricane Andrew, a Category 5 storm, spurred residents to prepare for the arrival of Hurricane Irma earlier than usual.
On Wednesday, Mr. Trump tweeted: “Watching hurricane closely. My team, which has done, and is doing, such a good job in Texas, is already in Florida. No rest for the weary!”
Most projections have Irma slamming into the state by Sunday, although it was unclear where it might make landfall.
Gov. Rick Scott activated the state National Guard and declared a state of emergency across Florida. During a Wednesday news conference, he pleaded with residents to heed advisories on whether to evacuate, and to act while the storm is still days away. Irma, he said, is more powerful and dangerous than Hurricane Andrew.
“Know your evacuation zone,” he said. “Listen to your locals. This storm has the potential to devastate the state. Take it seriously.”
The governor said that 1,000 National Guard troops would be on duty by Wednesday night, and ordered most state government offices closed on Friday. He urged people to stock up on basics and refill their prescriptions, and said the state was working to address shortages of fuel and bottled water.
Evacuation orders for Miami-Dade County were expected Wednesday or early Thursday, Mayor Carlos Gimenez said, as a precaution for what is expected to be unprecedented coastal flooding. The county expected to open shelters on Wednesday, and ordered schools closed on Thursday.
The Florida Keys, a vulnerable chain of islands, were under a mandatory evacuation order: Wednesday morning for visitors and Wednesday evening for residents. The islands’ three hospitals began evacuating patients on Tuesday.
Irma is expected to pass north of Puerto Rico, which could help the island avoid major damage, but the authorities still warned residents to watch for rising waters.
“We are letting people know there is an expectation of six to eight inches of rain, with some areas receiving up to 12 inches,” Gov. Ricardo A. Rosselló said at a televised briefing on Wednesday morning. “This is a cause of concern for flooding in Puerto Rico.”
Mr. Rosselló warned residents that authorities will suspend rescues once winds reach 50 mph. The government has activated 156 shelters on the island.
“As the history with Harvey states,” he said, in reference to the hurricane that battered Houston, “flooding can become the major cause of death in events of this nature.”
Police in Puerto Rico confirmed that a 75-year-old man in Orocovis died while preparing for the hurricane.
Officials warned that the island’s fragile electrical grid could be shut down for months in some areas.
The hurricane could hardly have come at a worse time for Puerto Rico. The island is the throes of an economic crisis and does not have money for rebuilding.
Tourists stranded on the island began receiving emergency instructions from hotel operators on Wednesday, who encouraged them to leave their rooms and shelter in hotel ballrooms to avoid the anticipated storm surge.
At the La Concha Hotel in Condado, the manager, Jose Suarez, told people that the storm was expected to intensify at 2 p.m. and last four to six hours, but that guests should expect to be there until Friday.
“We have never since 1928 experienced anything like this,” Mr. Suarez told guests gathered in the lobby on Wednesday morning. “This is very serious.”
Alex and Ally Tyre, a Jacksonville couple stranded in Puerto Rico on their honeymoon, had already prepared by moving the furniture in their room.
The Tyres married on Sunday and were on their way to Scrub Island in the British Virgin Islands when their flight was canceled, stranding them at their connection point, San Juan.
“We would feel safer if we were on the south side of the island,” Ms. Tyre said.
Antigua and Barbuda, which were expected to be hit by the full force of the storm, were rattled early Wednesday, but daylight revealed that the damage was less than expected.
“My first words must be of thanks,” began a statement from Prime Minister Gaston Browne of Antigua and Barbuda on Wednesday. “The forecast was that Antigua would be devastated, our infrastructure demolished, people killed and our economy destroyed. In the light of day, the picture is very different.”
He said his office had received no reports of deaths on either island.
Preliminary reports from Barbuda, he said, “indicate damage” to roofs and “to some buildings.” Irma tore the roof off a police station on Barbuda, forcing officers to take shelter in a nearby fire station, The Associated Press reported.
“The essential point is that our main infrastructure has stood up and our country can resume normal life within hours,” Mr. Browne said, including reopening the airport for arriving and departing flights beginning at 2 p.m.
He called the nation’s response to the storm “an exceptional story of resilience.”
In the Gambles Terrace neighborhood in St. John’s, the capital of Antigua, major structures were still intact and houses showed no significant damage. A few fallen branches littered the streets.
On Wednesday, Elias Hadeed, a retired structural engineer and general contractor in Antigua, said that from his perspective the storm was “much better than expected.” By 6 a.m., he said, the rain had stopped and there had been “no extensive damage” to his garden and his reinforced concrete home.
In St. Kitts and Nevis, Commissioner Ian Queeley of the Royal St. Christopher and Nevis Police Force said in a text message on Wednesday that the early reports were encouraging. “Not too bad at this time,” he wrote. “Still plenty rain and strong winds.”