They are brawling with a guy who is resisting them in a chaotic mess, the officers shout 'he's got a gun', a gunshot goes off, their reaction to assume he's got a gun and is firing it is pretty self explanatory and I shouldn't need to belabor that point.
I think people really get inured to overanalyzing of the split second decision making in chaotic life and death circumstances, like every police shooting being questioned as 'well even if the first two shots were justified, that third shot was murder~!' or 'why didn't he just shoot them in the legs' or so on
you arent getting what i said.
the officer had the gun. if it went off how did the other officers know it was suspects gun and he needed shooting?
the shot would have come from where the officer was which was away from suspect. so it could have been him shooting his own weapon.
you are saying if a cop hears a gun go off it means shoot anyone infront of you even if it was a fellow cop shooting.