REUTERS - Floodwaters from unprecedented rainfall in South Carolina have killed nine people, closed more than 500 roads and bridges and prompted hundreds of rescues of people trapped in homes and cars, officials said on Monday.

Governor Nikki Haley warned residents to remain on alert as rain continued to fall in some of the hardest-hit areas, including the state capital, Columbia, which saw its wettest days on record over the weekend.

"This is not over," Haley said at news conference. "There's still a lot of water out there."

President Barack Obama declared a disaster in South Carolina, making federal funds available to governments and non-profits in 11 counties.

More than 2 feet (60 cm) of rain have fallen in the past three days in parts of South Carolina, and moderate to heavy rain persisted on Monday in the state's saturated northeastern corner and in southeastern North Carolina, the National Weather Service said.

The flooding closed schools and government offices, stranded motorists and led to dramatic rescues, including a mother and her 15-month-old child who were plucked by a U.S. Coast Guard helicopter from a flooded home in Huger, South Carolina.

Five people drowned when floodwaters swamped their vehicles and four others died in weather-related car crashes, the state Department of Public Safety said. A state transportation department employee was killed after his work truck was overturned and swept away by rushing waters, the agency said.

The severe weather was also blamed for two deaths in North Carolina, officials said.

Nearly 1,000 people have found refuge in shelters around South Carolina, officials said, and water distribution centers were being opened after the downpours left an estimated 40,000 people without drinking water. About 26,000 were without power, officials said.

On Monday afternoon, the Richland County Sheriff's Department sent deputies door to door to warn residents to evacuate after a dam burst east of Columbia.

Condominium owners James and Rebecca Smith fled to a nearby high school gym that the county designated as a shelter. "I'm just worried about everybody else out there," said Rebecca Smith, referring to her 112-unit condominium complex.

In Columbia, police and fire officials were going door to door looking for anyone still be trapped in houses and to test the stability of buildings damaged by the deluge.

Columbia resident Tommy Rollins, 67, said he went to bed Saturday night after watching a football game and woke up at 4 a.m. Sunday to the sound of rushing water.

"It sounded like someone was taking a shower in every room," he said. "Within 10 minutes, water was bubbling up through the hardwood floors. We had about 30 minutes and then it was 4 feet (1.2 m) deep."

Rollins and his wife grabbed a change of clothes and some toiletries and stepped off their porch into chest-deep rushing water before being brought to safety in a neighbor's boat, he said.

Haley and meteorologists said more flooding concerns remain as rains in the Midlands and Upstate South Carolina flow downstream to the already-swamped area known as the Lowcountry.

That area includes the peninsula of Charleston, which emergency officials have reopened to allow people in and out though more than 30 streets remained flooded.

(Additional reporting by Harriet McLeod in Charleston, S.C., and Gene Cherry in Hatteras Island, N.C.; Writing by Colleen Jenkins)