It was expected to brush past the Florida Keys on Saturday and slam ashore on Sunday on the US coast along the Florida Panhandle, which was hammered by Hurricane Ivan in September. Residents were ordered to evacuate Key West and the lower Florida Keys, an island chain connected to the southern tip of Florida by a single highway.

"When Dennis gets into the Gulf of Mexico, this will be a whole statewide problem," said Florida state meteorologist Ken Nelson. "This is going to be a very large storm like Ivan."

Cuba evacuated thousands of people from central and southeastern parts of the island where heavy rainfall was expected, particularly in the Sierra Maestra mountains. Authorities warned of life-threatening flash floods and mudslides.

Strong gusts of wind before the hurricane knocked down trees in Santiago, Cuba's second-largest city, residents said.

Hurricane warnings were in effect for southwestern Haiti, Jamaica, the Cayman Islands, most of Cuba and parts of the Florida Keys.

At 5 p.m. EDT (2100 GMT), the center of Dennis was about 90 miles (145 km) southeast of Cabo Cruze in southeastern Cuba, the hurricane center said.

Its winds strengthened to 115 mph (185 kph), making it a "major" hurricane on the Saffir-Simpson scale, one capable of destroying mobile homes and doing structural damage to small buildings. Forecasters expected it to strengthen further before moving over Cuba.

HEAVY RAINS, MUDSLIDES

Dennis drenched Jamaica with heavy rains, triggering mudslides that blocked roads as the core of the storm moved north of the mountainous Caribbean island of 2.6 million on Thursday. About 3,000 Jamaicans moved to storm shelters in south-central Jamaica, which was battered by Hurricane Ivan in September.

Jamaica's airports shut down, supermarkets ran low on supplies as people stocked up on nonperishable goods, and schools were closed. Soldiers and police were put on alert to prevent looting.

Tourists in the coastal resort cities of Negril, Ocho Rios and Montego Bay snuggled into their hotels but were not asked to move to shelters.

"Not one tourist is panicking. Their only big concern is that those who have flights to board to the United States, Britain and other parts of Europe in particular, have not been able to leave because of the closure of the two international airports," said Patrick McGann, owner and manager of the Beachcomber Hotel in Negril.

Heavy rain flooded parts of southern Haiti, where wind gusts of 100 mph (160 kph) were recorded and civil defense officials advised residents in low-lying areas to take shelter in churches and schools. Three people were injured when a tree fell on a house in the town of Coteaux, but no deaths were reported, the officials said.

The storm also doused the Cayman Islands, a tiny British territory and banking center with 43,000 residents. Residents there were still rebuilding from Hurricane Ivan, which damaged or destroyed 70 percent of the buildings on Grand Cayman Island in September.

Dennis followed closely on the heels of Tropical Storm Cindy, which flooded streets and knocked out power to thousands of people around New Orleans this week.

It took a track similar to that of Ivan, which played havoc with US oil and natural gas production in the Gulf before striking the coast around Pensacola, Florida.

Florida prepared to send help to neighboring Gulf states if needed, but Division of Emergency Management Director Craig Fugate said, "It's probably going to be us asking for help."