Since it appears 5 police officers were in the group, they may have been wearing vest. You should also take penetration into consideration.
If you shoot a vest-wearing attacker on a bike with a 9mm round, he will cease attacking you.
From the pictures, it looks like these bikers were a black group. Is that correct?
WTF? I heard about one off duty cop who just stood by and watched, but I didn't see anything about there being cops in the biker group. Where can I confirm this?
Head shots....only head shots. Get good enough, get trained, get deadly.
If there were indeed 5 police officers in this motorcycle gang and they did nothing, then they aren’t off limits as aggressors in my book. Shoot them like any of the others.
In that case, you try for a head shot. It goes against what they teach you in firearms safety class, but when your survival is at stake all bets are off.