MORANT BAY, Jamaica -- A bridge collapsed into a river swollen by Hurricane Dennis' fierce winds and rain, killing at least four people in southwestern Haiti on Thursday as the strengthening storm lashed Caribbean coastlines.
The hurricane's winds neared 135 mph, and it grew to a Category 4 as it sideswiped Jamaica and headed straight for Cuba. Forecasters at the U.S. Hurricane Center in Miami predicted the storm could hit the United States anywhere from Florida to Louisiana by Sunday or Monday, raising fears that oil production in the Gulf of Mexico would be disrupted by the fourth storm in as many weeks.
Thunderstorms covered the Dominican Republic, southern Haiti and northeast Jamaica. The Cayman Islands and Cuba were under hurricane warnings, including the U.S. detention camp at Guantanamo Bay holding some 520 terror suspects.
In the southwestern Haitian town of Grand Goave, an Associated Press Television News reporter saw at least four people killed after the wood and metal bridge collapsed. Three were swept into the river, and witnesses said the river came suddenly rushing over the bridge.
Elsewhere on the dangerously deforested island, wind gusts uprooted a palm tree and flung it into a mud hut, killing one person in the southern town of Les Cayes, the Red Cross said.
The Florida Keys were under a hurricane warning Thursday and ordered tourists to evacuate, and the southern Florida peninsula was on tropical storm watch, expecting severe conditions within 36 hours.
In Jamaica, Prime Minister Percival Patterson urged people in low-lying areas to evacuate.
"Let us all work together in unity so that we will be spared the worst," Patterson said in a national radio broadcast. Despite his appeal, only about 1,000 people were in shelters late afternoon.
This is a "dangerous hurricane" that could strengthen considerably by early Friday, the hurricane center warned.
The hurricane center warned the eye could pass over central Cuba sometime Friday afternoon. In the communist-run island, where the military-style government has been praised by the United Nations for its extensive hurricane preparedness plans, more than 100,000 people had been evacuated in the island's southeast, civil defense officials said on state television.
There were no immediate plans to evacuate detainees or troops from the U.S. detention center's Camp Delta at Guantanamo Bay, located on Cuba's extreme southeast end about 150 yards from the ocean, Gen. Jay Hood said.
Troops put heavy steel shutters on sea-facing cell windows as heavy surf sent splashes of salt spray higher than the razor wire fence. Officials said Camp Delta was built to withstand winds up to 90 mph.
Oil prices rose sharply Wednesday on concerns about the Caribbean weather, but closed down 55 cents Thursday, at $60.73, a barrel, as a series of terrorist blasts in London led investors to abandon riskier investments.
Dennis came right behind Tropical Storm Cindy, which made landfall late Tuesday in Louisiana and hindered oil production and refining. On Thursday, remnants of Cindy dumped heavy rain on parts of the Carolinas, prompting flash flood and tornado watches.
Lead forecaster Martin Nelson said it was the first time the Atlantic hurricane season had four named storms this early since record-keeping began in 1851. The season runs from June 1 to Nov. 30.
In southern Haiti, gusts whipped sheets of rain that flooded roads and homes with up to three feet of debris-filled water. Tin roofs torn from homes and businesses tumbled in the wind. U.N. mission spokesman Damian Onses-Cardona said the biggest concern was that the rains would cause landslides on denuded mountains.
Last year, three catastrophic hurricanes -- Frances, Ivan and Jeanne -- tore through the Caribbean with a collective ferocity not seen in years, causing hundreds of deaths and billions of dollars in damage.
Haiti took the deadliest hit of last year's hurricane season when Jeanne, at the time a tropical storm, triggered flooding and mudslides: 1,500 people were killed, 900 missing and presumed dead and 200,000 left homeless. Torrential rains burst river banks and irrigation canals and unleashed mudslides that destroyed thousands of acres of fertile land in Haiti.
In Jamaica, where Hurricane Ivan destroyed 8,000 homes and killed 17 people last year, a power line was knocked down Thursday in eastern Morant Point and blocked the main coastal road.
"It's Dennis the menace," 34-year-old shopkeeper Wayne Brown said as he raced to box up sodas, canned food and bread from his small wooden store. He struggled to nail a blue tarp on the roof of the store, which was badly damaged by Ivan.
"It's one storm after another," he said. "I've never seen anything like it in all my years."
At 11 p.m. EDT, the storm was centered about 105 miles south of Camaguey, Cuba. It strengthened to a Category 4 storm -- the second-highest level on the Saffir-Simpson scale -- and was moving toward the northwest at 15 mph, the Hurricane Center said.
Hurricane force winds extended up to 50 miles from the center and tropical storm force winds another 140 miles.
Dennis could dump up to 15 inches of rain over the Sierra Maestra Mountains in southeastern Cuba and up to 10 inches over Jamaica's coffee-producing Blue Mountains, according to the Hurricane Center.