So far we know that at least 3 were shot outside the building and had no apparent connection to PP that the shooter would have known.
The cop who was killed was shot outside the building, FOX just reported that the Iraqi war vet was shot outside the building, and an aging hippie was shot in his car in the parking lot.
I'm not saying it can't be done, but someone shooting an AK over 200 yards who hasn't had either a lot of range time or doesn't have a good scope is doing pretty well, especially when the cop is likely behind his car if there is shooting going on. The first police officer down was bushwhacked, most likely, and not from by the corner of the PP building.