Xyth,
I just had a perfect situation in which I went into Pass-N-Gas, I attacked a zombie, but I only had a stone axe and suddenly a nurse NPC came from behind and finished that zombie for me. Soon after that, I looted the room, found a shotgun, went to the second room / garage, door was open and even before I reached it, a zombie that was inside went straight to me. I shot him and suddenly I had two bandits on my back, BanditEve and BanditArcher who both attacked me. That was probably a random rare coincidence, but it was pretty intense and very cool and it made me think that maybe it would be cool if wandering traders, bandits and npcs had a chance to be attracted to the sounds like shooting and follow the source. That could create some interesting situations like this one.