Gonzalo passed near Antigua as a tropical storm, tearing roofs from people's homes and knocking down trees, then gathered enough force near St. Martin to be reclassified as a hurricane.
"It's intensified at a pretty brisk pace since yesterday and we expect it to strengthen," said Michael Brennan, a senior hurricane specialist tracking the system from the US National Hurricane Center in Miami.
The storm was on track to take a turn away from Puerto Rico and the US Virgin Islands to the northwest. It was not expected to reach the US mainland but forecasters said it could develop into a major hurricane and pose a threat to Bermuda later in the week.
"It's certainly something that people in Bermuda will want to pay attention to," Brennan said.
As of 5pm, the center of Gonzalo was about 20 miles (30 kilometers) southeast of St. Martin and 140 miles (230 kilometers) southeast of St. Thomas. It had maximum sustained winds of 75 mph (120 kph) and was moving toward the northwest at 12 mph (19 kph).
For several hours, heavy rain and strong winds lashed Antigua, which bore the brunt of the storm as it cut through the northern Leeward Islands. Downed trees already blocked many island roads and many people lost power or reported that the storm damaged, or in some cases destroyed, the roofs their homes.
Condell Maurice, a 36-year-old teacher, said his roof sprung at least nine leaks during the storm. You should have seen us with our buckets, jugs and bowls trying to chase down those leaks," she said as she surveyed the damage, which also included several downed trees in her backyard.
Sherrod James, deputy director of the National Office of Disaster Services, said the agency has received reports of damaged homes but no injuries or deaths from the storm.
The government ordered schools and businesses to close amid an island-wide power outage and opened four emergency shelters.
Gonzalo is expected to produce up to 8 inches (20. centimeters) of rain across the Leeward Islands, the U.S. and British Virgin Islands and Puerto Rico.
Over the weekend, Tropical Storm Fay knocked out power to thousands in Bermuda before moving out over open ocean.
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