once i had read that there were multiple assailants involved, I couldn't figure out what his options would be if one was coming from behind - release suspect 1 and face suspect 2+, knock suspect 1 unconscoius with butt of gun and turn to face 2+? Not much of a choice.
Facts may or may not come out later but no one has discussed or suggested presence of a weapon other than the campus cop's.
If you look at the slideshow, the 2d picture shows a guy with a football jersey on. The word is that this guy tried to get Officer Jenkins away from the kid in the first picture. He was shot in the leg.
There are still a lot of unanswered questions.