CEDAR RAPIDS, Iowa (AP) – Hospital patients in wheelchairs and on stretchers were evacuated in the middle of the night as the biggest flood Cedar Rapids has ever seen swamped more than 400 blocks Friday and all but cut off the supply of clean drinking water in the city of 120,000.

As many as 10,000 townspeople driven from their homes by the rain-swollen Cedar River took shelter at schools and hotels or moved in with relatives.

About 100 miles to the west, the Des Moines River threatened to spill over the levees into downtown Des Moines, prompting officials in Iowa’s biggest city to urge people in low-lying areas to clear out by Friday evening. The river was expected to crest a couple of hours later.

“We are perilously close to topping the levees,” said Bill Stowe, public works director in the Iowa capital, population 190,000. He added: “It’s time to step out of harm’s way.”

The flooding was blamed for at least two deaths in Iowa: a driver was killed in an accident on a road under water, and a farmer who went out to check his property was swept away.

In Cedar Rapids, the engorged river flowed freely through downtown. At least 438 city blocks were under water, and in some neighborhoods the water was 8 feet high. Hundreds of cars were submerged, with only their antennas poking up through the water. Plastic toys bobbed in front of homes.

The Cedar River was expected to crest Friday night at nearly 32 feet, an astonishing 12 feet higher than the old record, set in 1929.

Gov. Chet Culver declared 83 of the state’s 99 counties disaster areas, a designation that helps speed aid and opens the way for loans and grants. The damage in Cedar Rapids alone was a preliminary $737 million, Fire Department spokesman Dave Koch said.

The drenching has also severely damaged the corn crop in America’s No. 1 corn state and other parts of the Midwest at a time when corn prices are soaring and food shortages have led to violence in some poor countries. But officials said it was too soon to put a price tag on the damage.

Cedar Rapids warned people to conserve drinking water after the floodwaters knocked out electricity to all but one of the city’s half-dozen or more wells. The one working well was protected by sandbags and generators that were pumping water away from it.

“If we lost that one we would be in serious trouble,” Koch said. “We really need to reduce the amount of water we are using, even using paper plates, hand sanitizer.”

Hotels implored guests to use water only for drinking.

The city’s newspaper, The Gazette, continued to cover the story with the help of emergency generators. But the floodwaters were just outside the front door, and the place had no running water. Portable bathrooms were set up outside for the staff.

“We’re putting the paper out through heroic, historic effort by the staff companywide,” said Steve Buttry, who started as editor of the newspaper on Tuesday – just one day before the disaster struck.

In Des Moines, fire officials had no immediate estimate of the number of people urged to evacuate several blocks close to the river. Mayor Frank Cownie said the evacuations were an attempt to “err on the side of citizens and residents.”

Floodwaters formed a near-moat around Principal Field, the Des Moines ballpark of the minor-league Iowa Cubs, a farm team for the Chicago Cubs.

Interstate 80 was closed east of Iowa City to Davenport after the Cedar River washed over the highway. Amtrak service aboard the California Zephyr was suspended between Omaha, Neb., and Chicago because of flooded-out tracks.

AP-ES-06-13-08 1800EDT