Three nights of heavy rainfall caused Iowa creeks and rivers to swell, forcing hundreds of residents from their homes and killing a 16-year-old girl when three cars were swept away by a torrent of water on a rural road.

In Ames, flooding contributed to a water main break that forced the city to shut off water to its roughly 55,000 residents and left Iowa State University's basketball arena under 4 to 5 feet of water.

The flooding in central and eastern Iowa on Wednesday followed three straight nights of strong thunderstorms. After a brief respite for much of the state, more thunderstorms were possible Friday and Saturday, according to the National Weather Service.

Divers found the body of Jessica Nichole Webb, of Altoona, near the submerged cars in Mud Creek on Wednesday afternoon, more than 10 hours after she disappeared. Authorities said fast-moving water had hindered earlier search efforts.

Three cars had been swept off the road between Altoona and Mitchellville about 4 a.m. Rescuers found 10 of the 11 passengers clinging to trees and hanging onto logs.

Doug Phillips, a division chief with the Polk County Sheriff's Office, said the creek is usually only 3 feet deep and 10 feet wide but early Wednesday morning, "it looked like a river."

Storms dumped 2 to 4 inches of rain on central and eastern Iowa overnight Wednesday, with 6 inches in some spots, the weather service said. A snowy winter and wet spring and summer "set the stage" for the flooding, but the recent storms were the big problem, meteorologist Jim Lee said.

"The bulk of this has been caused by those recent extreme rainfalls, especially back-to-back-to-back," he said.

The weather service issued a flash flood watch for northwest Iowa from Thursday afternoon through Friday evening, when more storms could bring up to 3 inches in some already saturated areas. Other parts of the state weren't expected to get more rain until later in the week.

Hundreds of residents in one Des Moines neighborhood were asked to leave Wednesday afternoon because of flooding by Four Mile Creek, and utility workers turned off natural gas and electric service to homes. A shelter was opened at an elementary school.

"It's such a serious and dangerous situation any time there is water around these homes because of the electricity and gas," police Sgt. Lori Lavorato said.

In Ames, about 30 miles north of Des Moines, officials shut off the city's water supply after saturated soil shifted under flooded Squaw Creek, causing a buried 24-inch main to fail. The break drained a city water tower, dropping pressure in the distribution system and raising the possibility the system's water could become contaminated.

Officials said repairs could take up to 24 hours and it might be a week before the water was safe to drink.

Several hundred Ames residents were evacuated after both Squaw Creek and Skunk River rose, Fire Chief Clint Petersen said. In some spots, water was up to car windshields.

The floor at Hilton Coliseum, Iowa State's basketball arena, was covered with up to 5 feet of water, school spokesman John McCarroll said. It was too soon to know how much damage had been done, he said.

Howe's Welding and Metal Fab had several feet of water inside it, even though the owners had been sandbagging all night. Piper Wall, whose husband owns the business, said it was difficult to assess the damage while the water remained, but it appeared worse than in 1993, when much of the area was underwater.

"It will be when all this comes out and all the mud that remains and the machining tools and electric stuff that's not high enough," Wall said. "In 1993, it was $150,000 and this year it's higher."

Downriver from Ames, the town of Colfax was nearly cut off by the rising Skunk River. Roads were covered by water, and people used boats to help neighbors. City officials asked at least 300 residents on the west side of town to move to higher ground, Colfax Mayor David Mast said.

Heather Kern's basement was flooded, and water was inching into the first floor with waste-high water in the backyard.

"I feel blessed that we have our lives," Kern said. "We don't know where we're going to live or where we're going to stay, but we have our lives."

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Associated Press writers Michael J. Crumb in Ames and Luke Meredith in Colfax contributed to this report.