People stand on the beach at the Westin Casuarina Resort and Spa as the Gustav storm system approaches along Seven Mile Beach on Grand Cayman Island Friday. (Brennan Linsley/Associated Press)

Hurricane Gustav plowed through the Cayman Islands toward Cuba late Friday, gathering strength on a journey that could take it to the U.S. Gulf Coast as a fearsome Category 3 storm three years after Hurricane Katrina.

Gustav, which killed 71 people in the Caribbean, swirled through the Caymans overnight with fierce winds that tore down trees and power lines. It was expected to cross Cuba's cigar country Saturday and head into the Gulf of Mexico by Sunday.

Gustav struck Cayman Brac and Little Cayman, the smaller easternmost islands in the chain of three. Storm surge and heavy rains flooded streets as people hunkered down in darkness at home or government shelters.

"We're just trying to wait it out," said Juliana O'Connor-Connolly, who represents the islands in the Cayman legislature, by cellphone from the kitchen of her farm on Cayman Brac.

She said about 40 people were riding out the storm in her home, which at 20 metres elevation is safe from flooding but still vulnerable to winds that ripped out hundreds of fruit trees on the farm.

"The wind is just tremendous," O'Connor-Connolly said at the height of the storm. "They say it's 80 m.p.h. [130 km/h] but it certainly seems to be over 100 m.p.h. [160 km/h], and I've been through lots of storms."

Late Friday night, Gustav was centered 40 kilometres west-southwest of Little Cayman Island and moving northwest near 17 km/h, according to the U.S. National Hurricane Center in Miami. Top winds were about 130 km/h.

Authorities in the Caymans did not impose a curfew but urged people to remain indoors to avoid interfering with emergency workers.

Hotels asked guests to leave and, after the airport closed, prepared to shelter those who remained. Chris Smith, of Frederick, Md., said his hotel handed out wrist bands marked with guests' names and room numbers so that "if something happens they can quickly identify us."

"That was a little bit sobering," he said, standing outside the hotel with his luggage.

The storm killed four people in a daylong march across the length of Jamaica, where it ripped off roofs and downed power lines. About 4,000 people were displaced from their homes, with about half relocated to shelters. Prime Minister Bruce Golding said the government sent helicopters Friday to rescue 31 people trapped by floods.

At least 59 people died in Haiti and eight in the Dominican Republic.

Better-than-even chance storm will hit New Orleans: forecasters

The U.S. hurricane centre said Gustav could grow to a Category 3 storm, with winds above 180 km/h, by the time it hits the U.S. Gulf Coast next week. Gustav could strike anywhere from the Florida Panhandle to Texas, but forecasters said there is a better-than-even chance that New Orleans will get slammed by at least tropical-storm-force winds.

As much as 80 per cent of the Gulf of Mexico's oil and gas production could be shut down as a precaution if Gustav enters as a major storm, weather research firm Planalytics predicted. Oil companies have already evacuated hundreds of workers from offshore platforms.

Gustav was projected to hit Cuba's Isle of Youth, then cross the main island into the Gulf of Mexico on Saturday night or Sunday. Cuban state television announced that effective Saturday, all buses and trains to and from Havana will be suspended until further notice.

Meanwhile, Tropical Storm Hanna was projected to curl westward into the Bahamas by early next week. It had sustained winds near 85 km/h late Friday.

Along the U.S. Gulf Coast, most commemorations of the Katrina anniversary were cancelled because of Gustav, but in New Orleans a horse-drawn carriage took the bodies of Katrina's last seven unclaimed victims to burial.

U.S. President George W. Bush declared an emergency in Louisiana, a move that allows the federal government to co-ordinate disaster relief and provide assistance in storm-affected areas.

New Orleans Mayor Ray Nagin said an evacuation order was likely, though not before Saturday, and the Federal Emergency Management Agency said it expects a "huge number" of Gulf Coast residents will be told to leave the region this weekend.