Iowa Gov. Chet Culver called the Boy Scouts at the Little Sioux Scout Ranch heroes for coming to the aid of other boys after a tornado flattened their camp site north of Little Sioux, killing four.

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Scouting executive Lloyd Roitstein said the boys lived up to the Boy Scout motto "Be Prepared."

He said they "knew what to do, they knew where to go and they prepared well."

Weather officials said Thursday that the tornado had initial estimated winds between 111 and 135 mph, rating it an EF-2, or Enhanced Fujita scale 2. Officials said the final rating could be EF-3 if the winds are determined to be stronger.

Four Scouts, two 13-year-olds and two 14-year-olds, were killed and 48 people were hurt Wednesday when the twister hit the Little Sioux Scout Ranch. The four Boy Scouts who died were all found near a collapsed stone chimney in a building that was leveled by the storm.

Josh Fennen, 13; Sam Thomsen, 13; and Ben Petrzilka, 14, all of Omaha were killed, along with Aaron Eilerts, 14, of Eagle Grove, Iowa, KETV in Omaha reported.

Fourteen other people were still hospitalized Thursday morning.

Officials scouring the park called it a total loss and said it was a "tragic day" for scouting.

Classmates and teachers praised the students who died as exemplary.

Robert Blue Middle School Principal Dawn Sievertsen said Aaron, an eighth-grader at his school, "was a wonderful kid."

"Fantastic -- (I can't) even begin to describe Aaron," Sievertsen said. "He was a great servant to the community. He was nominated for a state character award. He started a public service program called Pillow Cases for Patients. He made colorful warm pillowcases and sent them to area hospitals."

Andersen Principal Jeff Alfrey said Josh was a "quality Boy Scout and young man."

"Adventurous young man who I could see stepping up and being a leader," he said.

"Our thoughts and prayers are with the victims and their families," Culver said Thursday. "We are saddened by this tragedy, this loss of life."

'Tragic Day'

The tornado hit at 6:35 p.m., KETV reported.

There were 94 registered Boy Scout campers at the elite leadership training camp for a week, along with 25 adult and junior counselors. All of them sought shelter in two one-room cabins when the storm hit, Roitstein said.

"Today is a tragic day for Scouting," Roitstein said Thursday morning.

A Boy Scout official said the twister destroyed all the buildings and tents and most of the trees.

"The park is considered a total loss. It's completely destroyed," said Monona County Sheriff Jeffrey Pratt.

Said Roitstein to CNN: "All of the buildings are gone; most of the tents are gone; most of the trees are destroyed. You've got 1,800 acres of property that are destroyed right now."

Rescuers dug through piles of debris to reach trapped victims, some of them sheltering under tables. A rescue official said everyone at the camp has been accounted for.

U.S. Homeland Security Secretary Michael Chertoff toured the ruined camp on Thursday morning. He praised the response of the surviving Scouts as they worked to rescue their colleagues.

"We're shoulder to shoulder with all the communities of Iowa and Nebraska," Chertoff said. "This is a really terrible weather season for this part of the country. We want to support search and rescue, evacuation, and then we'll support our fellow citizens in the rebuilding."

He added, "It seems like the Boy Scouts didn't have a chance. It's truly a tragic act of God."

The National Weather Service issued two warnings minutes before the tornado hit, but it's not clear if the camp had sirens.

Roitstein said some Scouts were out hiking Wednesday afternoon, but had weather radios and a response plan in case severe weather struck. Roitstein said the boys had already sought shelter in the camp's two main structures when the tornado touched down.

"Scouts practice being prepared every day. They had weather radios and talked about storms and discussed where to go," Roitstein said.

Roitstein described the camp as a wilderness experience and a rustic environment. He said no basements exist on the campgrounds and the two buildings where the Scouts sought shelter are not built to stand up to the wind.

Roitstein said the campers had discussed emergency procedures on Tuesday and practiced first-aid techniques.

Rescue Effort

Many of the 13- to 17-year-old campers immediately started applying their rescue skills after the storm hit, the TV station reported.

A group of three boys broke into a storage shed, took an all-terrain vehicle and a chain saw and headed to the area of the camp hardest-hit to start freeing trapped campers and administering first aid, Roitstein said.

A group of boys also went to Ranger Nathan Dean's home on the campgrounds to rescue his family from the remains of their home, which was demolished in the storm. Dean lives at the property full time as a caretaker. Roitstein said Dean's wife was hospitalized for her injuries.

A.J. Loson, one of the Scouts on the staff at the camp, said that after the tornado passed, he went to the ranger's house, which had collapsed. Loson said he heard a child crying and people calling for help from the rubble.

"We found out where their voices were coming from," Loson said. "It seemed like there was an entire house just piled on top of them. We just pulled off everything we can. There was a chair, a couch, we got some cinder blocks, two-by-fours, doors and all sorts of things until we finally found where they were closer together."

More than 100 volunteers from the community also went to the camp to help.

"I want to honor them for what they did," Nebraska Gov. Dave Heineman said of the Scouts and volunteers.

Dozens Hospitalized

In all, 42 people were taken to hospitals for their injuries.

A 15-year-old said he was in a building when it collapsed on him. He is hospitalized with a possible broken rib.

A boy released from the Blair hospital said he was sitting down to watch a movie when the storm hit. He was inside a building, and when he went toward the door, it blew open and knocked him to the ground.

Camper Ben Karschner said it was over quickly.

"Eight seconds and the tornado passed. That was like the longest eight seconds I've ever had," he said.

Iowa Braces For More Flooding

Nearly 4,000 homes have been evacuated in Cedar Rapids, Iowa, as the state braces for more flooding following 5 inches of rain overnight.

Mandatory evacuation orders were in place as well Thursday for parts of Iowa City and Coralville. Forecasters are keeping a wary eye on the confluence of the Raccoon and Des Moines Rivers in downtown Des Moines.

More than half of Iowa's 99 counties have been declared disaster areas by the governor and nine rivers are at or above historic flood levels.

In southern Wisconsin, federal disaster officials were assessing flood damage even as more heavy rain was moving into the area. The National Weather Service issued a flash flood warning for the Wisconsin Dells area, including Lake Delton, which overflowed and drained into the Wisconsin River earlier this week.

Deadly Tornado Hits Kansas

In northern Kansas, two people are dead after tornadoes cut a diagonal path across the state Wednesday night, authorities said.

A spokeswoman for the Kansas Adjutant General's Department said one victim was found in a yard in the town of Chapman. The other was found outside a mobile home in the Jackson County town of Soldier.

Tornadoes also touched down in southern Minnesota and eastern Nebraska.