Without saying a word, a mysterious man in black clutching a semi-automatic pistol opened fire on a California bar packed with college students celebrating "country night" Wednesday — claiming the lives of at least 12 patrons, including a veteran sheriff's sergeant nearing retirement, before officers found the gunman dead. Hundreds of people -- including students from California Lutheran University, private Christian school Pepperdine University and California State University Channel Islands -- were inside Borderline Bar & Grill in Thousand Oaks, Calif., for the country music event when shots suddenly rang out at about 11:20 p.m., Ventura County police said. Police...