We have trained people to do exactly the wrong thing and that is to try to get away. Everyone should immediately close on the shooter. Yes the shooter might get one or two people but even they might survive since they would already be moving in. It only takes a split second for multiple people to close in and subdue a single person. More importantly once crazies know this is what will happen they won't even do it to begin with.
Once we make it known to all the would be lone gunman mass murderers that as soon as they fire the first shot they will be ATTACKED from every direction they will cease having ideas of these mass shooting all together. The last thing these nut jobs want is a fight, especially a fight they know they won't win. They want people to panic and wait to die so they can kill then either kill themselves or get killed by the police. They DO NOT want to get jumped on restrained then spend the rest of their miserable lives in prison. That fear alone will stop these shootings.
Now if you want to arm teachers or people at work fine but it's not really needed when you are talking about a lone gunman. Mace or a taser combined with everyone closing on the shooter would be just as effective if not more. The lone gunman mass murderer is the EASIEST of all killers to stop. Much easier problem than say stopping a 2 ton truck mowing down people on a sidewalk or a terrorist planting a bomb. Those problems are hard to solve.
>The answer to a lone gunman is very simple. Everyone jump on the shooter
Yep. The human instinct is the wrong one here; people, especially young people, can close the distance way faster than the bad guy can act.
Jump the perp, then do what a pack of wolves would do to an enemy of the pack. Screw prison.