REMINDER: It’s very unlikely you will ever confront an active shooter, but if you do: run as far and fast as you can in the opposite direction of where the gunfire is coming from, and if possible don’t hide somewhere where you are cornered/trapped. If you do find yourself cornered in a room or closet, don’t just sit there and wait for the gunman to find you, have a plan (with your fellow cornerees) to confront and attack the gunman from each side of the  door as soon as he opens the door, and if you are in hiding an the gunman doesn’t appear, don’t come out until authorities give the all-clear signal. That’s what I learned in my State Department security training, and it’s advice that would have saved lives in several recent incidents. It’s undoubtedly very hard to keep these things in mind under the stress of the situation, but much easier if you have it firmly in your mind in advance.