 This is a special report from ABC News. Trump assassination attempt. I'm Mark Remillard. The FBI identifying the gunman who opened fire at former President Trump's rally in Butler, Pennsylvania, killing a spectator, wounding Trump in the ear and injuring two others. The FBI says 20-year-old Thomas Matthew Crooks opened fire from a rooftop a few hundred yards from the venue. Secret Service returned fire shortly after killing Crooks. FBI Special Agent in Charge Kevin Rojack says they're looking into Crooks' background