Zach Jessen, 14, recalled the scene for "GMA."
"They saw a rotation in the clouds," recounted Jessen. "We all grabbed our stuff from one building. We went outside. The alarm went off. We woke up everybody. We got the people to the shelter just in time, just before the tornado hit."
When the twister struck, "the door on the building flew open and all I heard was 'Get under the tables, get under the tables!' So I got under there."
Jessen said he used his body to cover the head of another boy.
"Then all of a sudden the tornado came and took the building with it. … There were some tables there. They weren't bolted down though. Some were thrown out. The chimney in the building was completely gone, too."
Jessen said he saw nothing while the tornado was overhead, but when he looked up after it passed there was little to recognize.
"From what I saw, it was just one giant pile of stuff," he said.
Jessen said living through the tornado was an experience he will never forget.
"I think if I can survive a tornado, I can pretty much survive anything right now," he told GMA.
When heavy rains began that night, between 40 and 50 people left their tents and moved inside a roofed shelter, scout Hal Emas told the Des Moines Register.
Emas says he and a friend grabbed on to a picnic table and one of the metal poles left sticking in the ground.
"Everything was destroyed. The whole campsite was destroyed."
Camper Taylor Willoughby said several scouts were getting ready to watch a movie when one of them screamed that there was a tornado. While they ducked down, the twister struck, smashing windows.
Willoughby, who was treated at Burgess Health Center for a bruised back, said he saw a fellow scout with his head split open. "It was a pretty gruesome image."
Ethan Hession, 13, crawled under a table with a friend.
"I just remember looking over at my friend, and all of a sudden he just says to me, `Dear God, save us,"' he told NBC's "Today" show. "Then I just closed my eyes and all of a sudden it's [the tornado] gone."
The scouts told similar stories of what happened when the violence was over and bleeding scouts were left kneeling on the remains of the camp or buried in debris. They organized themselves and helped one another.
Hession described how one staff member took off his shirt and put it on a bleeding victim, applying pressure and gauze.
"We knew that we needed to place tourniquets on wounds that were bleeding too much. We knew we needed to apply pressure and gauze. We had first aid kits, we had everything," Hession said.
'We got together and started undoing the rubble from the fireplace and stuff and were pulling kids out and waiting for the first responders," staff member Thomas White told CNN.
"We were able to get the kids calm. … All of that preparation and all of the scouting we've done helped out. It really paid off last night," White said.
Jessen said the scouts had actually prepared for just such a disaster a few days earlier.
"We just did a realistic first aid where somebody got dressed up in fake gash on his right arm, and he bursts through the door. So that pretty much helped the participants to know what to do for the tornado."
After news of the tornado, frantic scout leaders and parents rushed to the scene, desperately trying to find their loved ones.