So, due to the recent events of this shooting and the one at the Sikh Temple, we had a Police Officer that runs the Homeland Security aspect of our city stop by our Mosque prior to the nightly prayers (which I'm about to go too.) Basically, he went over things about what we should do if heaven forbid, an event like that were to happen at the Mosque or anywhere else for that matter. Thought I'd share what he said if heaven forbid, you guys were in this situation.
In order of priority...
1. Evacuate the room/building. Usually done if you know for sure you can get away from the shooter or if he has his attention somewhere else.
2. Hide. If the shooter is in the same room as you, all you can really do is try to conceal yourself.
3. Don't be a sitting duck. You're better off trying to neutralize him by either throwing things at him or trying to take him down. You will get shot at if you just stand there or turn your back to him. If you make an effort to stop him, you can save another life.
Some other things he mentioned.
A. Once outside, do not "point" with your finger at the Cops or anywhere else. In a tense situation, a cop might see a "point" and register instantly as a gun. Keep your fingers wide open.
B. Do not talk to the Officers unless it is to tell them information on the shooter. The paramedics will take care of the injured. An officer's job is to take down the suspect, so that he does not hurt anyone else.