Seems like if the father was going to shoot, he should have hit the guy with the gun.
he did.
Nick Buell shot at (and seems to have hit) ArmedPerpAlpha; His son, Frank Buell, was under the gun of ArmedPerpBeta.
The elder Buell could not see what was going on with his son.
we do not know from this report whether PerpGamma was Armed or not.
I recommend you change your screen name...........................