One thing I think should be brought up in this is that everyone who responded and said "empty the mag", "two to the chest", "double tap", "two to the chest one to the head" is giving horrible advice.
You shoot to STOP, period.
This is the best post on this thread IMHO. You shoot until the threat is gone, even if that means you have to unload 18 rounds from your Glock, and reload to keep shooting. If your first shot is a head shot that eliminates the threat right away, dont shoot anymore.
That pharmacist probably could have handled that better, IIRC he was using a 5-shot S&W snubby, he took the time to go and reload his revolver, only to shoot the BG 5 more times, at point blank range