I teach at a college. Given the unabated stream of shootings at schools and workplaces, I'm going to start including the five steps of "How to Survive a Mass Shooting" in my syllabi. I'm almost hesitant to allow the culture of mass shootings to be normalized in any way, but my students' safety comes first. I also think that if people start using the following tactics regularly, shooters may be less drawn to create a situation in which they can feel ultimate power, because people will have tools to own the power shooters are trying to steal.
Attention to what we can do at the microlevel is not intended to distract from the importance of seeking macrolevel solutions. But the steps are on the flip, and none of us should think we'll never have to implement them.
The hierarchy of actions in a shooting event are
RUN
HIDE
FIGHT
More detailed instructions can be found at
WikiHow: How to Survive a School or Workplace Shooting and
ABC News: Run, Hide, or Fight: Eleven Tips to Survive Mass Shooting
BE PREPARED Keep your wits about you and do not let yourself be paralyzed by fear. Being aware that you have options at hand that may save your life can keep you from freezing up at a critical moment.
DO SOMETHING Whatever you do, do not succumb to freezing up.
RUN Your best chance of survival is to flee. Be on the lookout for alternate routes. If possible, crouch and run as low as you can. Run in a zig-zag pattern to make yourself a hard target. Leave personal belongings behind; every second may count.
HIDE If you determine that you can not flee safely, the next best step is to hide. Barricade yourself if possible and silence your cellphone. If you can, dial 911 from a landline so that your call can be traced by dispatchers should you need to break off the call.
FIGHT If you can not evade an attacker, fight him (and chances are very high that it will be a him). Use any item you can - pen, scissors, fire extinguisher - as a makeshift weapon. Pleas for mercy or attempts to reason will likely be ineffective given the mental state of the attacker. Keep in mind that not all gunshots are lethal and focus on fighting the attacker over trying not to get shot. When possible, fight as a group.
WHEN EMERGENCY SERVICES ARRIVE Do not reveal yourself; you may create confusion and become a target for police. Wait for emergency services to bring the situation under control and follow directions.