I don't believe for a second that someone with a concealed weapon would have stopped the shooting had he not known of his presence. But I do think that if someone was alerted to the gunman's presence taking him down would have been more likely. It would have been unlikely that there would have been a three hour killing spree.
I do believe that one person with a concealed weapon would have minimized the loss of lives; not that he had some kind of spidey sense to prevent the unthinkable.
But if the timelines are accurate, and a hostage situation actually did occur, I think it would have been possible for a concealed weapon carrier to shoot the guy at some opportune time.
Our text for Sunday School (also "The Confession of Faith and Catechisms") Biblical Theology Bites What is "Biblical Theology...