An investigation is underway regarding the death of an Iraq war veteran and amputee who was thrown from a roller coaster at an upstate New York amusement park Friday night, MSNBC reports. Thomas Hackemer of Gowanda, N.Y. had been rebuilding his life after a warhead explosion in 2008 caused brain damage and forced the amputation of his legs. It wasn't immediately clear if attendants at Darien Lake Theme Park Resort had considered barring Hackemer from the ride because of his missing limbs. Passengers on the Ride of Steel coaster are held in by a bar that sits across their legs, according to MSNBC. Hackemer's mother said that her 29-year-old son had likely died happily. "He was doing what he wanted to do," she said.