BLENCOE, Iowa - A tornado slammed a Boy Scout camp in the remote hills of western Iowa yesteday, killing at least four people and injuring 40, most of whom were on a hike when the twister struck.

All of the children had been accounted for late last night, after rescuers cut their way through downed trees and debris to reach them, said Russ Lewrenson of the Mondamin Fire Department.

A search-and-rescue team had been deployed to the camp near Little Sioux, Iowa Homeland Security spokeswoman Julie Tack said.

At least 40 people who were injured in the storm were being taken to area hospitals. Most of the kids who were hurt were out on a hike when the tornado hit, Lewrenson said.

There were 93 campers, ages 13 to 18, and 25 staff members at the leadership-training camp. "They were considered some of the best in the area," Tack said.

The ranch about 40 miles north of Omaha, Neb., includes hiking trails through narrow valleys and over steep hills, a 15-acre lake and a rifle range.

"All of the buildings are gone; most of the tents are gone; most of the trees are destroyed," Lloyd Roitstein, president of the Boy Scouts of Mid-America Council, told CNN. "You've got 1,800 acres of property that are destroyed right now."

The tornado touched down as Iowa's eastern half grappled with flooding in several cities. The storm threatened to further stretch Iowa's emergency response teams.

Earlier in the day, inmates in striped uniforms were rescued from jail by boat as the raging Cedar River flooded a small Iowa city's downtown and forced evacuations in another town downstream.

From Wisconsin to Missouri, officials in the flood-ravaged Midwest frantically sandbagged, watched weakened dams, and rescued residents from water that in some places rose knee-high, while storms threatened more damage in the Upper Plains.

Officials in Wisconsin were monitoring dams, and high water in Indiana burst a levee, flooding a vast stretch of farmland. In Minnesota and North Dakota, strong winds closed a highway and even sent a cow into the air, a witness said. Tornadoes also touched down in eastern Nebraska and southwest Minnesota, but there were no immediate reports of major damage.

Along the Mississippi River in Missouri and Illinois, the National Weather Service predicted the worst flooding in 15 years.

"Everything is flooded - everything is up to knee-high," said Patrice Calhoun of Waterloo, Iowa, who rolled up her pants and waded through water to get home yesterday. "You could actually swim in it."

Much of downtown in nearby Vinton was flooded, forcing officials to empty the county jail.

In Cedar Falls, officials were relieved that a frantic volunteer sandbagging effort had kept floodwaters out of downtown.