Well, shooting mom and pop after being scared of the big guy son, hmmm. Did Mom and Dad present an imminent, grave and reasonable threat to the off duty officer s well? I have my reservations now.
There had better be both video and as many credible witnesses for the defense of justification proof.
I’m guessing all three were “in his face” when he decided to open fire.
Just a guess.
They may have been trying to rescue their son, who was in the process of being killed, or even trying to pull him out of an argument before the shooting. Or, they might have been going after "a bad guy with a gun" (they likely had no idea he was a cop). At this point, as bad as it looks, we just don't know what happened. Still, it's hard to imagine a situation that required shooting the whole family.
There should be video from several cameras. Hopefully the parents survive and can give their side...