Dramatic footage from Cambridge, MA, shows an armed suspect after he was shot by a responding Massachusetts State Police trooper. Authorities identified the gunman as Tyler Brown. Brown allegedly fired 50 to 60 rounds indiscriminately from an assault-style rifle as he erratically walked down Memorial Drive in Cambridge around 1:20 p.m., Middlesex County District Attorney Marian Ryan said during a press conference. At least two people were treated for life-threatening injuries following the shooting.