While there is still a "blackout" on recent news from the authorities, that story was based on a Dec. 15 NBC report and was apparently based on bad info? Not unlike some of the other garbage the media rushed onto the airwaves, about his mom being a teacher at the school, etc.
No surprise, as the news media these days would sooner blurt out bad info as rapidly as possible, than wait to get the actual facts before flappin' their gums on TV. See it everyday.
That pompous [censored] of a state medical examiner, said that the shooter used an AR, during his self-serving news conference about a week ago.