In nearby Puerto Rico, residents flocked to stores to stock up on supplies and jammed roads after government offices and businesses shut down early. One death was reported on Puerto Rico's tiny island of Culebra. Authorities say a 55-year-old man collapsed from cardiac arrest while trying to install storm shutters on his house.
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 for all islands. 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."
Police already rescued several stranded motorists from flooded roads by late Wednesday afternoon. Police Commissioner James H. McCall warned that anyone found on the roads after curfew would be taken into custody.
Jerry Comparitivo, a teacher who lives in St. Croix, said he could see dark clouds gathering as the sun set.
"I am tying up the loose ends right now, and getting ready with my family to hunker down for what could be a very eventful night," he said.
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.
Most residents spent the day securing their homes and making sure they had enough food, water and batteries.
"I plan to stay up all night and ride out the storm, but I have a feeling it's going to be very bad," said Helino Cruz, a Hovensa retiree.
Hurricane warnings were also in place for Anguilla, St. Maarten, and St. Barts. A tropical storm warning was issued for Antigua, Barbuda and Montserrat.
At a restaurant in St. Maarten, diners traded war stories about previous hurricanes. But Joel Pinas remained quiet as he remembered the three months he endured without power after Hurricane Luis rumbled through in 1995.
"When there's a hurricane approaching, I always get worried," he said.
Hurricane Omar forced at least three cruise ships to divert course. Flights were canceled on several islands.
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.
At 8 p.m. Wednesday, Omar's center was located 80 miles (130 kilometers) south-southwest of St. Croix and 135 miles (215 kilometers) miles south-southeast of San Juan, Puerto Rico. It was moving northeast near 17 mph (28 kph).
Meanwhile, another tropical depression was hugging the coast of Honduras, and a tropical storm warning was in effect for the area.
Associated Press writers Andrew O. Selsky in San Juan, Puerto Rico; Judi Shimel in Charlotte Amalie, U.S. Virgin Islands; and Marvin Hokstam in Philipsburg, St. Maarten contributed to this report.