Yes Rob, I have thought about it, I think 1st respond, seek cover, don't just freeze, if your the 1st close target, ( Well do what you got to do

) once behind cover, call 911 or try to angle the shooter if your armed, a point of discussion, it seems to me in an environment with lots of bystanders, shots if possible, should be taken from kneeling or prone to promote an upward angled shot, that would pass over the heads of said bystanders in the event of a pass through. My favorite scenario in my head, is a movie theater both inside and outside, Both brightly lit and very low light, many targets for an active shooter, and many targets to avoid if your trying to counter that shooter. By favorite, I mean worst nightmare. Lots of sheep at the movies. Once in the room, mark those exits in your head, make a plan. As always, get training.
Me, I wait for it to come on HD TV.
Responses?