Tropical storm Irene has strengthened into a hurricane after it began moving across Puerto Rico, bringing torrential rains and winds and threatening to move toward the US later in the week.
Earlier Irene downed trees and caused widespread power cuts in the US Virgin Islands as it churned just miles from St. Croix.
Forecasters initially said Irene was likely to pass south of Puerto Rico, but the storm shifted north and was passing directly over the island.
Early today Hurricane Irene was moving west-north-west at roughly 12 miles per hour with maximum sustained winds near 75 miles per hour. The centre was about 25 miles west of San Juan, Puerto Rico.
After moving over Puerto Rico, Irene was expected to approach Hispaniola, the island shared by the Dominican Republic and Haiti. Nearly 600,000 people in Haiti still live without shelter after last year's earthquake.
In the US, Irene, the first hurricane of the Atlantic hurricane season, was expected to affect Florida and could clip Georgia and the Carolinas.
The US hurricane centre said the main impediment to the storm's progress over the next couple of days will be interaction with land. If Irene passes over Hispaniola's mountains or over parts of eastern Cuba, the storm could weaken more than currently expected.
"However, if the system ends up moving to the north of both of those land masses it could strengthen more than expected," it said.