Tropical Storm Isaac took aim at the Dominican Republic and Haiti early Thursday, expected to gain strength after drenching tiny islands in its whirl over the eastern entrance to the Caribbean.

No major damage was reported, but authorities in Puerto Rico said an elderly woman died in an accident while preparing for the storm.

U.S. forecasters said Isaac was likely to approach Hispaniola, the island shared by the Dominican Republic and Haiti, as a hurricane late Thursday or early Friday after intensifying over the warm waters of the Caribbean Sea.

It was predicted to move on to Cuba as a tropical storm and perhaps eventually menace Florida as a hurricane later in the week.