I once heard an assessment of the Paduka Kentucky school shootings. The assessment was done by a PHD in psychology from Arkansas College. He was also a retired Army Infantry LTC and and a combat veteran.
For those of you who do not remember this 1997 shooting, I have posted the following link:
The shooter fired 8 rounds and killed three and wounded five. All of the victims were moving. His actual shooting experience was minimal but, he had spent hours playing video games.
The LTCs major point was that in that situation running was what drew the shooters attention.
Based on his assessment, I think the best bet is to move away from shooting low and cautiously. Try not to draw attention to your self and chargees.
The advice about going into a store and using the back exit or a service entrance to evacuate is outstanding. If the attack is a coordinated terrorist action then the main exits will be covered by bg and or an IED.
If armed, I would (probably) not engage a shooter unless directly confronted.
If forced to confront a shooter(s), I would be in fear of the responding LEOs.
Some suggestions from our experienced LEOs on how to handle a post engagement would be good at this point.