INDIANAPOLIS (AP)  -- A possible tornado toppled trees in Nebraska and record flooding chased people from their Indiana homes on Sunday, as the Midwest braced for still more violent weather.

At least one person downed in the Indiana flooding and one was missing since more than 10 inches of rain swamped the state this weekend. Twenty-one counties had been declared disasters, said John Erickson, a spokesman for the Indiana Department of Homeland Security.

Boats were the only way to get around a number of Indiana neighborhoods on Sunday, after flood waters started forcing hundreds of people to evacuate their homes. And forecasters warned that the next two to three days could see some rivers overflow to historic levels.

In Michigan, two delivery workers for The Grand Rapids Press drowned early Sunday when their car became submerged in a creek that washed out a road, the newspaper said.

The National Weather Service forecast more damaging weather across the Midwest, and posted severe storm warnings for parts of Illinois and Wisconsin.

The rising White River led officials in the southern Indiana city of Seymour to order a mandatory evacuation of more than 100 homes Sunday morning.

Record flooding also continued along the Wabash and Flatrock rivers, Erickson said. A Johnson County dam was breached by the high water but had not failed, he said.

``It's in bad shape,'' Erickson said.

Shelters set up in the southern Indiana city of Columbus were filled with people, Erickson said.

More than 250 patients and employees were evacuated from Columbus Regional Hospital in southern Indiana, and 150 residents were taken out of a flooded nursing home in Morgan County, southwest of Indianapolis.

Water reached the first floor of Johnson Memorial Hospital in Franklin, but no patients had to be moved, county Commissioner Tom Kite said, and cars were submerged up to their windshields in the county government building parking lot.

He also said there were dams endangered by high water in the Prince's Lakes area, threatening the town of Nineveh about 30 miles south of Indianapolis.

Flooding also forced 430 people staying at a Columbus-area high school to move to another shelter.

Erickson did not have details about the drowning. One person was reported missing after falling off an airboat in a flooded area, state police 1st Sgt. Dave Bursten said.

In Omaha, Neb., a possible tornado touched down, smashing a tree onto a house. No deaths or major injuries have been reported.

Rain continued falling Sunday in Wisconsin, where a day earlier strong storms with baseball-size hail and high wind blew roofs off homes, toppled trees and power lines, and injured at least six people.

State emergency management officials evacuated two dozen people living in a trailer park in De Soto ahead of rising water.

Illinois residents were measuring the damage caused by Saturday's twisters in Chicago's suburbs, where minor injuries were reported.

The floods in Indiana threatened dams, inundated highways and forced the Coast Guard to rescue residents from swamped homes. Rising waters forced the evacuation of more than 100 patients and doctors from a hospital south of Indianapolis.

To the northwest, Chicago-area residents ran for cover as tornadoes touched down throughout the region on Saturday. About 25,000 customers in Chicago's southern suburbs were without power at one point.