Felony murder at work.
You commit a felony, any reasonably anticipatable bad outcome that results is your fault. A bystander being hit certainly counts as something bad that could happen.
If it's mutual combat they're both guilty. If one was trying to avoid the situation (doesn't sound like it) then only the other is guilty.
The race of the perps and the fact that the cop was incompetent has nothing to do with this.
Personally, I'm not concerned about the race of the perps and how that may or may not have affected the behavior of the police. I'll give them that. My issue is with telling police officers it's ok to shoot everyone because the blame will be placed on whomever or whatever caused you to shoot. "Have at it!" It's counterproductive to that whole don't harm civilians during training thingamabob. Would make a good scene in Police Academy though: Cadet blasts away at every target that pops up
"What the hell are you doing?"
"Stacking charges sir!"
"Carry on then".
Saying that the shooters are guilty of felony murder doesn't make the cops blameless. You're not limited to one charge per victim.