DES MOINES, Iowa (AP) -- Officials on Friday issued a voluntary evacuation order for much of downtown Des Moines, Iowa, and other areas bordering the Des Moines River.
Floodwater laps at the doors of Mercy Medical Center in Cedar Rapids, Iowa, on Friday.
The alert was prompted by rising river levels expected to peak at 8 p.m. Friday.
Des Moines Mayor Frank Cownie said officials chose "to err on the side of citizens and residents."
The evacuation should begin immediately and be completed by 6 p.m., the mayor said.
In Cedar Rapids, a downtown hospital was evacuated as the Cedar River flooded 400 city blocks.
Residents of more than 3,000 homes fled for higher ground and a railroad bridge collapsed.
The hospital's 176 patients, including about 30 in a nursing home facility, were being transferred to other hospitals in the region.
The Cedar Rapids evacuation started late Thursday night and continued Friday morning in the city of 124,000 residents.
"Some are frail and so it's a very delicate process with them," said Karen Vander Sanden, a hospital spokeswoman. Watch how folks are coping in Cedar Rapids »
Water was seeping into the hospital's lower levels, where the emergency generator is located, said Dustin Hinrichs of the Linn County emergency operations center.
"They proactively and preventatively started evacuation basically guessing on the fact they were going to lose power," he said.
Dave Koch, a spokesman for the Cedar Rapids fire department, said the river will crest Friday at about 31.8 feet. It was at 30.9 feet early in the morning. In a 1993 flood, considered the worst in recent history, it was at 19.27 feet. iReport.com: Teen takes pics during sandbagging run
"We are seeing a historic hydrological event taking place with unprecedented river levels occurring," said Brian Pierce, a meteorologist with the National Weather Service in Davenport, Iowa. "We're in uncharted territory -- this is an event beyond what anybody could even imagine." Watch how weather is bludgeoning the Midwest »
Flooding also closed Interstate 80 from east of Iowa City to Davenport. The flooded Cedar River crosses the interstate in Cedar County, about 20 miles east of Iowa City.
Iowa Gov. Chet Culver declared 83 of the state's 99 counties state disaster areas. Nine rivers are at or above historic flood levels. Amtrak's California Zephyr line was suspended across Iowa because of flooding along the BNSF Railway.
No deaths or serious injuries were reported in Iowa, but two men died in their cars in southern Minnesota and western lower Michigan.
In Wisconsin, amphibious vehicles that carry tourists on the Wisconsin River were used to evacuate homes and businesses in Baraboo, north of Madison. Hundreds of people lost power in Avoca, west of Madison, and were "strongly encouraged" to evacuate due to flooding, said Chief Deputy Jon Pepper of the Iowa County Sheriff's Department. iReport.com: Duck boats to the rescue
The rising Fond du Lac River forced hundreds from homes in Fond du Lac.
Violent thunderstorms Thursday and Friday brought widespread flooding to Michigan's Lower Peninsula that authorities say left some roads and bridges unstable or impassable. Authorities in Mason County advised drivers to stay off the roads unless it was an emergency, and the county closed or barricaded more than a dozen roadways.
People in several northern Missouri communities, meanwhile, were piling up sandbags to prepare for flooding in the Missouri River, expected to crest over the weekend, and a more significant rise in the Mississippi River expected Wednesday.
Despite all the water in Cedar Rapids, there was precious little for toilets, cleaning, or drinking.
Koch said the city is at critical levels and only one of the city's six wells was operating.
"If we lost that one we would be in serious trouble. Basically we are using more water than we are producing," he said. "We really need to reduce the amount of water we are using ... even using paper plates, hand sanitizer."
Similarly, the town of Lawrenceville, Illinois, grappled with a broken water system that left businesses with no usable tap water, forcing them to close.
In Cedar Rapids, rescuers had to use boats to reach many stranded residents, and people could be seen dragging suitcases up closed highway exit ramps to escape the water.
"We're just kind of at God's mercy right now, so hopefully people that never prayed before this, it might be a good time to start," Linn County Sheriff Don Zeller said. "We're going to need a lot of prayers and people are going to need a lot of patience and understanding." Watch what Iowa has to look forward to »
Prisoners had to be moved from the Linn County jail, including some inmates who had been transferred from the Benton County jail in Vinton because of flooding. The sheriff's office also was underwater, Zeller said.
The surging river caused part of a railroad bridge and about 20 hopper cars loaded with rocks to collapse into the river. The cars had been positioned on the bridge in hopes of weighing it down against the rising water.