IMHO, I don’t give darn if the animal control officer was on scene. If a dog is free and lunging at people, I have no problem with an officer shooting it to protect himself or others.
The dog was shot from the back of it’s head. If it was chasing a student at the time, than the student was in the DIRECT pathway of the bullet.
When you are at the range, I doubt you will fire your weapon if you see any people DIRECTLY in the path of your bullet.