But the first deaths he witnessed were American soldiers returning from a mission in Iraq just after dawn. "We saw something that looked like a buried IED (improvised explosive device) in the road, but we couldn't stop them. The first vehicle went over it. Then the second went over it. It exploded, and everyone died," he says. "I was 19 at the time and I felt guilty, as though I was responsible for the deaths of our military members. That's when I knew I would never be the same again."