Oct. 16 (Bloomberg) -- Hurricane Omar weakened quickly today as it picked up speed in the open Atlantic Ocean after sweeping over the Virgin Islands, where it forced a curfew and closed an oil refinery.

Omar's maximum winds fell to 85 miles (140 kilometers) per hour from 125 mph earlier today, making it a Category 1 storm on the Saffir-Simpson scale, the National Hurricane Center said in an advisory just before 11 a.m. Miami time.

The storm is moving northeast at 23 mph, and is now 180 miles northeast of the northern Leeward Islands, moving into the central Atlantic.

``We had a whole heap of wind and water,'' Maria Robles, the night attendant at the Divi Carina Bay Resort in St. Croix, said today in a telephone interview.

U.S. Virgin Islands Governor John deJongh Jr. closed schools, sent non-essential government workers home and ordered a curfew that began at 6 p.m. local time yesterday, according to a statement on his Web site. The Public Works Department was distributing sandbags on all of the territory's islands.

``We will vigorously enforce this curfew as it is necessary that we clear the streets and avoid persons becoming injured,'' Police Commissioner James McCall said in the statement.

Outside the King Christian Hotel at Christiansted, St. Croix, two boats sank and another was smashed against the concrete dock. At the Buccaneer Hotel, also on St. Croix, many trees lost branches or were uprooted, a security officer said by phone.

Eye of Omar

The worst of the storm had passed the French islands of St. Barthelemy and St. Martin/Maarten by 5 a.m. local time, Meteo- France, the government forecaster, said in a statement on its Web site. As much as 5 inches of rain fell on St. Martin, it said.

``The strong rains have ended, though showers may persist,'' the agency said. There will be ``rapid improvement of the wind and rain this morning.''

Omar may bring as much as 6 inches of additional rain to the northern and central Lesser Antilles, the center said.

On Montserrat, authorities were monitoring the effect heavy rains might have on the island's Soufriere Hill volcano. They ordered an evacuation of parts of the island because of the risk of the volcano's dome collapsing and the threat posed by mudflows of volcanic ash and water, the country's Disaster Management Agency said.

Vigilance Urged

``The entire population is asked to be vigilant in the light of proposed increased rainfall which could cause severe flooding,'' the agency said on the Montserrat Volcano Observatory Web site. ``Residents are being asked not to traverse watercourses during intense rainfall and farmers are asked to move animals from these channels before it starts raining.''

St. Croix in the Virgin Islands is the site of the Hovensa LLC oil refinery, the third-biggest in the Americas. Hovensa shut down processing equipment at the facility, Alex Moorhead, a spokesman for the plant, said yesterday by telephone.

The refinery, which according to federal data handled 456,000 barrels a day in July, wasn't damaged by the storm and is restarting, according to Far Chette, director of enforcement for the Virgin Islands Department of Planning and Natural Resources. The refinery is owned by Hess Corp. of New York and Venezuela's state oil company, Petroleos de Venezuela SA.

To contact the reporters on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net; Alex Morales in London at amorales2@bloomberg.net.

Last Updated: October 16, 2008 11:52 EDT