Reply #97: One does like in the OP -- calls police. If they arrive in time great. Then, you try to reason

[Hoyt]

with the gun toter -- which is obviously a losing proposition because the mere fact they carry a gun into a family restaurant shows they are irrational. You do your best to detain them, short of capturing the reprobate and opening yourself to charges by those who can't leave home without a gun. Then, you get their license number and any other identifying info. And, finally, you chase them down the street yelling at them for polluting society.

There's more.