Authorities on Thursday identified the gunman who opened fire and killed at least 12 people at a California bar as 28-year-old Ian David Long. A veteran of the Marine Corps, Long entered the Borderline Bar & Grill in Thousand Oaks, California, at about 11:20 p.m. Wednesday night, using a .45-caliber handgun with an extended magazine on it, Ventura County Sheriff Geoff Dean said. A county sheriff's sergeant, Ron Helus, was among those killed in the mass shooting. The shooter was found dead in the bar, and police say they believe he shot himself. Witnesses have said that the suspect was dressed in all black and wearing glasses. A motive has not been identified.

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