Something to be aware of is “sympathetic firing” (taken from “sympathetic detonation” of explosives.
One cop shoots, they all shoot. It first came to attention in the Ammadou Diallo case in NYC.
https://en.wikipedia.org/wiki/Killing_of_Amadou_Diallo
Boy howdy did they turn that guy into swiss cheese.
Diallo that is...
It's also a military principle. It doesn't matter that you don't know what he's shooting at, you support your buddy's fire, without exception.