SANTO DOMINGO, Dominican Republic - Flash flooding from Tropical Storm Olga's torrential rains killed at least eight people in the Dominican Republic and forced tens of thousands out of their homes, government officials said on Wednesday.

Olga was also blamed for mudslides that killed a man in Puerto Rico.

The storm weakened on Wednesday to a tropical depression after it exited Hispaniola, the island shared by Haiti and the Dominican Republic. But flooding remained a deadly threat as the remnants of Olga moved west across the Caribbean, forecasters at the U.S. National Hurricane Center in Miami said.

By late afternoon, Olga was just a broad mass of thunderstorms centered 65 miles (100 km) north of Kingston, Jamaica. It was moving rapidly west on a course that would keep the center south of Cuba and take it over Mexico's Yucatan Peninsula by Saturday.

Olga's top sustained winds dropped to 35 mph (55 kph), below the threshold to be called a tropical storm, and forecasters expected it to dissipate further on Thursday.

But the system was expected to drench the southeast Bahamas and eastern Cuba, while dumping several more inches of rain on Hispaniola, where totals could reach 10 inches (25 cm), forecasters said.

In the Dominican Republic, heavy rains sent the Yaque del Norte River over its banks in the northern city of Santiago.

Rushing waters submerged and flipped cars, and sent panicked residents to the treetops and rooftops.

Government authorities confirmed eight deaths but local media reports put the death toll at 15, and scores of people were missing. Some died as the flood waters collapsed their homes while other were dragged away by the water.

Helicopters plucked victims from rooftops and police moved hundreds of prisoners from a flooded jail to an army fortress. More than 24,000 people were unable to return to their homes after the storm passed.

There were widespread power outages and several communities were cut off by rising rivers that flooded bridges and highways in the mountainous country, where at least 89 people died in floods from Tropical Storm Noel in October.

In Puerto Rico, mud and rocks rained onto a highway west of San Juan early on Wednesday, injuring a motorist and killing his passenger. Police said the victim, a 23-year-old man, was "trapped between the mudslide and the avalanche of rocks."

Several roadways in that island's central mountains were closed because of fallen rocks and debris.

Olga, the 15th named storm of the year, formed in the Virgin Islands on Monday, 10 days after the official end of the six-month Atlantic-Caribbean hurricane season.

Tropical storms feed on warm seas, so December storms are unusual. Olga was the 17th named storm to form in the region in the month of December since record-keeping began in 1851, the hurricane center forecasters said.