Check out this video from CNN.  It shows an ideal response to the least ideal scenario possible.   Obviously the man in the video was diligent, but it also is apparent that he's got a trained background.

Maybe you don't work in any kind of security field, but how will you react if you find yourself under pressure and fire in a "dynamic critical incident" such as this?   No one will know until it happens, but if you have taken the time to prepare, think, learn, and practice, you tip the odds back into your favor in almost any situation.

Don't be paranoid.  Be aware.  Be alert.  Be prepared.