[RonPeeredob]

An armed civilian on the street would have no reason to confront the guy in the first place.

Sounds like George Zimmerman.

The only situation in which an armed civilian could interject themselves into a situation like this would be if the perp was waving the gun around, pointing it, and/or actually shooting. Oh really?

So it's not possible that an armed civilian might have witnessed the shooting from the distance, saw the perp walking away, and decided to chase after him? After all, he's armed. So the cops arrive and are confronted by two civilians with handguns.

Is this the landscape you want?