How does this happen? I'd love to know the motivations and perspectives of people involved. Did they make a mistake? Were they confused? If so, what was their line of thought? Did they try to intentionally cause harm to innocent people? If so, what was the reason.

Also, is this a rare unusual occurrence, or does this happen 75%+ of the time you call 911?

It just seems like a situation that should not have happened the way it was described (which may or may not be accurate).