Disturbing indeed. I can only reason a heightened state on the officer's side bc obviously they were chasing the bikers. You can see after the guy took off too fast from the stop sign, the officer was in pursuit with the lights on. It looked like they were trying to run away, since they didn't pull over right away.
Having served as a juror on a case involving police officers before, it seems he followed procedure by calling backups, etc, up until the point where they stopped. At that point they should have tried to control the situation by voice commands (i.e. Ottawa police, put your hands in the air, etc). That's when it looks like he jumped the gun literally. And honestly, from the footage presented, I cannot figure out why he went in pursuit anyway - the guys didn't seem to speed, did full stops at the stop signs...
Disturbing.