Well yes, some scenes are kind of violent I guess. But those "shooting" scenes would have been more extreme if the camera angle was different. (like showing the shootings from the front instead of from the behind) I think a rating of "High" will do for this anime.
It has battles in them for sure and as some people pointed out some of the Kurumi scenes are pretty dark. However since most of it is censored I can't really put this show in the extreme category. I am kinda hanging between medium and high, I'll for now vote it High due to some of the scenes it has but don't be too scared off by this since the violence is only high at moments.