If you are not in the habit of carrying a concealed handgun daily, I recommend that you consider doing so wherever it is legal. Recent shootings in the US highlight the fact that shootings can occur at any place, at any time.
During the last year, shootings have occurred in schools, shopping malls (Salt Lake City’s Trolley Square & Omaha, NE), churches, the workplace, etc. If you have a means to protect yourself and your family, you are less likely to panic during such an event because now you have options. You should have the mindset that you “refuse to be a victim.”
Your “mindset” is your biggest variable in your survival. Condition yourself to prevail regardless of the circumstances (multiple assailants, you are injured, etc.). The biggest problem is letting panic rule your judgement.