CHARLOTTE AMALIE, U.S. Virgin Islands – Schools, businesses and a large oil refinery closed Wednesday on several Caribbean islands in the path of Hurricane Omar, which could rev up to a Category 2 storm before coming ashore overnight.

U.S. Virgin Islands Gov. John deJongh closed all public schools, told government employees to head home at midmorning and imposed a 6 p.m. curfew on the islands of St. Thomas and St. John. He also activated the National Guard.

“Take this very seriously,” he said. “Folks are out right now doing their last minute shopping, and that's understandable. Once that's done, we encourage them to go home.”

To the west in Puerto Rico, government offices closed early, adding to traffic jams as islanders headed home or sought emergency provisions. Omar should pass near Puerto Rico early Thursday morning.

One death was reported in the neighboring island of Culebra. Authorities say a 55-year-old man collapsed from cardiac arrest while trying to install storm shutters on his house.

In the British Virgin Islands, residents flocked to supermarkets for supplies. To protect against deadly shocks from downed power lines, the electricity will be turned off across the territory once winds reach 40 mph (65 kph), said government spokeswoman Sandra Ward.

“Hospitals are in emergency mode,” Ward told The Associated Press. “They have generators and confirmed they have backup generators filled with diesel and ready to go.”

In St. Croix, the Hovensa LLC oil refinery, among the 10 largest in the world, was shutting down until after the storm passes, said spokesman Alex Moorehead. St. Croix is the most-populous of the U.S. Virgin Islands with more than 50,000 people. It stood in the direct path of the late-season storm, which could grow into a Category 2 storm before driving over the islands after midnight.

Hurricane warnings were also in place for Anguilla, St. Martin, and St. Barts. A tropical storm warning was issued for Antigua, Barbuda and Montserrat.

The storm forced diversion of Carnival's Triumph cruise ship to Jamaica and Grand Cayman, away from stops in St. Thomas and San Juan, spokeswoman Joyce Oliva said. Carnival's Glory ship canceled a stop in St. Maarten on Wednesday and will instead visit Grand Turk.

Royal Caribbean's Mariner of the Seas also canceled stops in St. Thomas and St. Maarten, opting to visit Grand Cayman and Cozumel in Mexico instead.

Officials in the U.S. Virgin Islands expected to cancel all flights Wednesday afternoon. In Puerto Rico, American Eagle, Delta, Jet Blue, Spirit, LIAT, Cape Air and Vieques Air Link canceled flights and US Airways said it expected to cancel a Philadelphia-bound flight on Thursday.

Authorities in Puerto Rico also prepared shelters in Vieques and Culebra.

Omar was a Category 1 hurricane with winds near 90 mph (150 kph).

The National Hurricane Center in Miami said Omar was expected to plow over the northeastern Caribbean islands then head into the central North Atlantic, well away from the U.S. mainland.

Omar's center was located about 150 miles (245 kilometers) southwest of St. Croix and 175 (280 kilometers) miles south of San Juan, Puerto Rico, at 5 p.m. Wednesday and was moving northeast near 15 mph (24 kph).

Meanwhile, another tropical depression was hugging the coast of Honduras, and a tropical storm warning was in effect for the area.