The spinning core of tropical storm Gustav was expected to move back over open water on Friday, a day after bearing down on southern Jamaica.

The tropical storm hit Jamaica on Thursday after leaving 67 people dead in Hispaniola, the island divided between Haiti and the Dominican Republic. The US states of Texas and Louisiana put their national guards on standby, and New Orleans said a mandatory evacuation might be necessary.

At least 59 people died in Haiti from floods, mudslides and falling trees, including 25 around the city of Jacmel, where Gustav first struck land on Tuesday. Eight more people were buried when a cliff gave way in the Dominican Republic. Marcelina Feliz died clutching her 11-month-old baby, and five more children were smothered in the wreckage beside her.

At 2am EDT (0600 GMT) on Friday, the storm was centered on Jamaica’s southwest coast, about 60 miles (95 kilometers) west of Kingston and moving west near 8 mph (13 kph). Gustav’s maximum sustained winds had decreased to near 65 mph (100 kph). But forecasters said it could strengthen into a hurricane before slamming into Grand Cayman on Friday.

There were no immediate reports of casualties in Jamaica, but many people lost power on Thursday and the streets of Kingston were deserted as heavy winds and rain lashed the capital.

Even as tourists searched for flights off the islands, officials urged calm. Theresa Foster, one of the owners of the Grand Caymanian Resort, said Gustav didn’t look as threatening as Hurricane Ivan, which destroyed 70 per cent of Grand Cayman’s buildings four years ago.

“Whatever was going to blow away has already blown away,” she said.

Forecasters said parts of Jamaica could get 25 inches (63 centimeters) of rain, which could trigger landslides and cause serious crop damage.

By early Thursday evening, dozens of roofs were ripped from houses, trees were toppled and many roads were left impassable by floodwaters and debris.

Jamaica evacuated low-lying areas including Portmore, a crowded and flood-prone area outside Kingston. Kingston’s main airport was closed and buses stopped running even as people streamed into supermarkets for emergency supplies.

Oil prices spiked above $120 (Dh442) a barrel before settling below $116 in a session made volatile by fears that the storm could affect production in the Gulf area, home to 4,000 oil rigs and half of America’s refining capacity. Hundreds of offshore workers pulled out, and analysts said the storm could send US gas prices back over $4 a gallon.

“Prices are going to go up pretty soon. You’re going to see increases by 5, 10, 15 cents a gallon,” said Tom Kloza, publisher of the Oil Price Information Service in Wall, New Jersey. “If we have a Katrina-type event, you’re talking about gas prices going up another 30 per cent.”

Meanwhile, Tropical Storm Hanna formed in the Atlantic, but it was too early to predict whether it could threaten the US east coast. Forecasters cautioned that Gustav’s path remained equally uncertain.

“It is simply impossible to determine exactly where and when Gustav will make final landfall,” said Richard Knabb of the National Hurricane Center in Miami. “The chances of hurricane-force winds within the next five days are essentially the same at each individual location from the Florida Panhandle coast westward through the entire coastline of Louisiana.”

But with Hurricane Katrina’s third anniversary falling on Friday, Louisiana wasn’t taking any chances. Gov Bobby Jindal declared a state of emergency to lay the groundwork for federal assistance. Texas Gov Rick Perry issued a disaster declaration, and together they put 8,000 National Guard troops on standby.

New Orleans Mayor Ray Nagin said he would order a mandatory evacuation of the city if forecasters predict a Category-3 strike – or possibly even a Category-2 – within 72 hours. Both Jindal and Nagin were meeting with US Homeland Security Secretary Michael Chertoff.

“I’m panicking,” said Evelyn Fuselier of Chalmette, whose home was submerged in 14 feet (4 meters) of Katrina’s floodwaters. “I keep thinking, ‘Did the Corps fix the levees? Is my house going to flood again?’ ... ‘Am I going to have to go through all this again?’”