There are other countries with similarly high rates of gun ownership and divergently lower rates of police firearm deaths.
The problem is in the police culture towards discharging a firearm, not the greater ownership of guns. American society bears much of the blame for lionizing cops instead of scrutinizing them.
Many cases of police officers killing innocent civilians involved civilians who were either fleeing, submitting, or already subdued and pinned down. Cops in the US tend to be exonerated for using deadly force, even when the victim could not arguably have endangered others.