KINGSTON, Jamaica — Tourists and oil workers fled Thursday as Gustav swamped eastern Jamaica on a path to hit the Cayman Islands with winds near hurricane force. Louisiana called a state of emergency and put the National Guard on standby, hoping to avoid the chaos of Hurricane Katrina three years ago.

Gustav swirled away from the island of Hispaniola, where it killed 23 people in Haiti and the Dominican Republic, and closed in on Jamaica's low-lying capital, about 40 miles (65 km) to the west. Forecasters said Gustav could hit Jamaica as a hurricane by Thursday night and perhaps hit Grand Cayman Friday night.

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 percent of Grand Cayman's buildings four years ago.

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

Gustav was lashing Jamaica with tropical storm-force winds, and forcasters said parts of the island could get up to 25 inches (63 centimeters) of rain, which could trigger landslides and cause serious crop damage. Authorities told fisherman to stay ashore, and hotel workers secured beach umbrellas in the resort city of Montego Bay.

Oil prices jumped above $120 a barrel Thursday on 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 as analysts said the storm could send U.S. 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, N.J. "If we have a Katrina-type event, you're talking about gas prices going up another 30 percent."

In the Atlantic, meanwhile, Tropical Storm Hanna formed on a course that pointed toward the U.S. east coast. It was too early to predict whether Hanna could threaten land, but Gustav was causing jitters from Mexico's Cancun resort to the Florida panhandle.

With top sustained winds just below hurricane strength, Gustav was projected to become a major Category 3 hurricane after passing between Cuba and Mexico and entering the warm and deep Gulf waters. Some models showed Gustav taking a path toward Louisiana and other Gulf states devastated by hurricanes Katrina and Rita.