Heavy rain hits a dangerous crescendo in South Carolina

A car is submerged in floodwaters in Florence, S.C., on Oct. 4, 2015. (Gerry Broome / AP)

COLUMBIA, S.C. -- Hundreds of people were rescued from fast-moving floodwaters Sunday in South Carolina as days of heavy rain hit a dangerous crescendo that buckled buildings and roads, closed a major East Coast interstate highway route and threatened the drinking water supply for the capital city.

The powerful rainstorm dumped more than 30 centimetres of rain overnight on Columbia, swamping hundreds of businesses and homes. Emergency workers waded into waist-deep water to help people trapped in cars, dozens of boats fanned out to rescue people in flooded neighbourhoods and some were plucked from rooftops by helicopters.

Officials said it could take weeks or even months to assess every road and bridge that's been closed around the state. Several interstate highways around Columbia were closed, and so was a 120-kilometre stretch of Interstate 95 that is a key route connecting Miami to Washington, D.C., and New York.

"This is different than a hurricane because it is water, it is slow moving and it is sitting. We can't just move the water out," South Carolina Gov. Nikki Haley said at a news conference.

One death was reported in the area on Sunday, bringing weather-related deaths to seven since the storm began days earlier.

People were told to stay off roads and remain indoors until floodwaters recede, and a curfew was issued for Columbia and across two surrounding counties. The capital city told all 375,000 of its water customers to boil water before drinking because of water line breaks and the threat of rising water to a treatment plant. Nearly 30,000 customers were without power at one point.

State forecasters said another 5 to 15 centimetres could fall around the state, and it could be Tuesday before skies are sunny. The rainstorm around the Southeast has drawn tropical moisture from offshore that's linked up with an area of low pressure and a slow-moving front.

Local officials counted several hundred water rescues by mid-morning before Columbia Fire Chief Aubry Jenkins said in an interview that there were too many rescues to keep count.

One of the hardest hit areas in Columbia was near Gills Creek, where a weather station recorded more than 45 centimetres of rain -- or more than a third of the city's average yearly rainfall -- nearly all of it in 24 hours. The creek was three metres above flood stage, spilling floodwaters that almost reached the stoplights at a four-lane intersection.

Vladimir Gorrin said he led his 57-year-old aunt through floodwaters about 2.1 metres deep surrounding her apartment near Gills Creek. He said his aunt, Wanda Laboy, waited several hours after calling the emergency dispatcher, so family came to help.

"She's very distressed right now," said Gorrin, 38. "She lost everything."

Emergency shelters were being opened around the state for displaced residents, and President Barack Obama declared a state of emergency in South Carolina.

Along the coast, rainfall had exceeded 50 centimetres since Friday in some areas around Charleston, though conditions had improved enough that residents and business owners were allowed downtown on a limited basis.

Charleston Mayor Joe Riley said he's never seen flooding as bad in his 40 years as mayor.

"This was a record storm," he said. "You know the amount of rainfall that we have experienced is unprecedented. I feel very fortunate that we were able to get through this as well as we have."

The latest death reported was a woman killed when her SUV was swept into flood waters in Columbia. Richland County Coroner Gary Watts said the woman's body was found Sunday afternoon, about 12 hours after she disappeared in flood waters near downtown Columbia.

Contributing to this report were Associated Press writers Bruce Smith in Charleston, South Carolina; Mitch Weiss in Greenville, South Carolina; Jonathan Drew in Durham, North Carolina; and Susanne Schafer in Columbia.