 and prompted questions about how a gunman was able to open fire from a rooftop near a Pennsylvania campaign rally. The FBI says they're investigating the deadly shooting as a potential act of domestic terrorism and have identified the gunman as 20-year-old Thomas Matthew Crooks of Bethel Park, Pennsylvania, about 50 miles from the scene of the shooting. One of the suspect's former classmates told ABC News that the shooter was picked on in school and was largely a loner. He'd wear hunting outfits sometimes.