 although our investigators are working tirelessly to attempt to identify what that motive was. The FBI says the shooter was 20-year-old Thomas Crooks of Bethel Park, Pennsylvania, a Secret Service sniper shot and killed Crooks, who had an AR-style rifle. This doctor tried to help a man who'd been hit. I heard the shots. I thought it was firecrackers to begin with. Somebody over there was screaming, he's been shot, he's been shot. So I made my way over. I said, I'm an emergency department physician.