Engaging a Shooter in a Crowded Space

[Zincwarrior]

Assumption #3: They are a stone cold sociopath bent on killing. They are highly perceptive, scanning for threats, taking in everything and carefully choosing their targets.

Newb answer who has benefit of years of experience...drinking coffee:
*Duck down in the footwell with Wife. Chairs are big barco lounger types with room for both of us and we tend to sit on the side (seats are arranged in groups with side seats on wall, and big center area. Engage only if BG moves into visual range where he is able to see us. Empty mag into BG if that happens (M&Pc).

Sorry I can't think of what else I would do given the parameters that he's carefully targeting those fleeing, and assuming he came in from the entrance or the fire escape.
Hoping to read better plans than mine.

[Duelist]

Newb answer who has benefit of years of experience...drinking coffee:
*Duck down in the footwell with Wife. Chairs are big barco lounger types with room for both of us and we tend to sit on the side (seats are arranged in groups with side seats on wall, and big center area. Engage only if BG moves into visual range where he is able to see us. Empty mag into BG if that happens (M&Pc).

Sorry I can't think of what else I would do given the parameters that he's carefully targeting those fleeing, and assuming he came in from the entrance or the fire escape.
Hoping to read better plans than mine.

That sounds pretty workable, given that you have a number of unarmed dependents to protect.

[LOBO]

One thing to think about regarding taking a knee to angle up a headshot is does your church have a balcony? Something to think about.

[Duelist]

One thing to think about regarding taking a knee to angle up a headshot is does your church have a balcony? Something to think about.

Or angled/stadium seating...

[Hambo]

I know this is an over-simplified description of an extremely chaotic, unpredictable scene

Yes, it is. How can you prepare for 500 no-shoots, the carnage of a MCI, and the possibility of being killed by the shooter, the police, or another person with a CCW? I'm not sure you can but what I'd really recommend is finding some force on force training, maybe Craig Douglas, but something that at least exposes you to a lot of stress and how to work through it.