Call it what it is.

Negligent discharge. Keep your finger off the trigger and the muzzle in a safe direction, and this s**t don't happen.

Police accidentally shot man in North Miami, union says

[UPDATE]
I saw this after the post.

North Miami SWAT Cop Shot Therapist In Order To “Save” Him From Unarmed Autistic Man

The officer fired at the autistic man three times with his rifle and MISSED hitting the therapist instead. This despite the therapist telling the officers what the true situation was. OK. Give the officer the benefit of a doubt you still have a case of legal but negligent. The officer took a chance on a shot with the therapist in the line of fire and came up snake eyes. Clearly not an accident. Sucks to be him.