"This incident" is a person, a young girl, who deserves to be protected and to have her attackers punished severely.
They broke the law, period. This should have been reported immediately.
And why do these "students" have unsupervised time hanging out in gangs in the cafeteria/gym?
I went to school in the late 60's and early 70's to Dublin when Dublin was nothing more than a country school. Dowtown Dublin was a traffic light and two gas stations. You couldn't even buy a loaf of bread in town at that time. You wouldn't believe some of the stuff that went on there. I did witness some touching and feeling in some of the more remote areas of the school. While it never in what I saw degenerated into oral or penetrational sex on school grounds, I saw more than my fair share of nipples and pubic hair. And I hung with the better behaved kids. The teachers simply didn't have the time or the numbers to keep track of all of us.
As I said, let's not white wash this, but let's also not make it a media circus. We need improvment, not just simply geting a couple of peoples scalps. This is a serious problem that is going to take time, effort and clear minds.