LE as a whole is not responsible for this incident, the officer in question is. Either the officer did not follow his training, or.... he lost control. Either way he should be held accountable for his actions, removed from the force, and charged. Many people, without malice hit someone in the street or have an accident and kill someone, they are charged, it must be heard by the courts.
Now if its found that he did not have adequate training, then his dept up the line is to be held responsible. I believe this officer had his finger on the trigger (which you never do unless you are going to shoot), that combined with an adrenaline dump, I think he messed up. I hope he will come clean on it. IMHO
The officer in question and the detachment he works out of is responsible. He's not alone - someone sent him out there.
The officer, the people he reports to and those responsible for conducting justice in a court will come clean? We'll see.
Jmo.