Nearly 30 teenagers were rushed to the emergency room at Cook Children's on Tuesday afternoon. They suffered head trauma, broken limbs, nausea and disorientation. One young man even had a piece of dock wood stuck in his chest.

Fortunately, it's all part of a last-minute mass casualty drill that helps keep nurses and doctors prepared for the worst should it occur.

"We see it all. Head injuries, as well as chest injuries. Foreign bodies into their chest," says Dr. Daniel Guzman, one of the ER's top doctors.

Guzman treated a number of the "patients," who were actually local high schoolers covered in fake blood and assigned injuries to simulate a real-life boating accident.

"Having kids come in dressed, anytime you have this many kids coming into the ER, you get pumped," says Guzman.

Staff only had 10 minutes of warning before the kids were unloaded from a MedStar AmBus, a giant ambulance of sorts used in mass casualty events.

Alex Enzi, 17, is participating in a drill for the second time.

This year, she's suffering from head trauma, including a broken noise, black eye and other ailments.

"It actually feels very real," she said.

Before the drill begins, each of the kids spend about five to seven minutes getting doctored up with fake blood, injuries, and make up to simulate what could happen in a real tragedy.

Enzi says that part is actually fun.

"It's interesting, and I'm really interested in medicine and care," she said. "Everyone here is."

The hospital does similar exercises throughout the year, although the focus on a boating accident was something they wanted to practice given that so many families are out on area lakes this time of the summer.