Tropical Storm Olga triggered floods and landslides in the Dominican Republic Wednesday, killing seven people and forcing thousands to flee their homes.

Hardest hit was the northern province of Santiago, where heavy rains prompted authorities to release water from a near-capacity dam into the already swollen Yaque River.

The provincial governor said at least seven towns were completely flooded.

People complained on local radio that they were not warned of the water release from the dam, and officials acknowledged it might have caused some of the deaths.

Dominican Republic Attorney General Radhames Jimenez said 5,000 people evacuated their homes before the deluge of water hit.

"We have an emergency situation. It's a catastrophe," Gov. Jose Izquierdo said.

As heavy rains began to overwhelm the Tavera Dam outside Santiago, the country's second-largest city, officials gave the order to begin releasing millions of gallons per second into the river, said Ismael Matias, planning chief of the country's emergency operations centre.

Local authorities had warned repeatedly that a release was possible during the storm and told people to evacuate areas in the path of floodwaters rising as high as 20 metres above normal, Matias said. It was unclear whether the warnings were heeded or even relayed.

Puerto Rico also hit hard

The storm was also blamed for one death on Tuesday in Puerto Rico, where an avalanche of mud buried an SUV. Olga also knocked out electricity to 79,000 people and water to 144,000.

A tropical storm warning was in effect for the southeastern Bahamas and the Turks and Caicos Islands, meaning tropical storm conditions are expected there within 24 hours.

Olga struck nearly two weeks after the official end of the Atlantic hurricane season. It is only the 10th named storm to develop in the month of December since record keeping began in 1851, according to the U.S. National Hurricane Center in Miami.

"It's not completely unusual to have a storm form in December," said hurricane specialist Daniel Brown, who noted that three named storms have formed after Nov. 30 since 2003.

The storm passed through the southwestern areas of the Dominican Republic that were hardest hit by Tropical Storm Noel six weeks ago. At least 87 deaths in the country were blamed on Noel, the deadliest storm of the 2007 Atlantic hurricane season.

Olga will be included in the tally for the 2007 hurricane season, bringing the number of named storms to 15, including six hurricanes. The next season begins June 1.