I wonder why no one interfered? It was a somewhat public place.
Call 9-1-1 and (watch while another person) dies.
or
Zero tolerance thing, you know, fight with the perp and get kicked out for fighting, and if you took his knife away from him and and hurt him with the knife, you would be thrown out of school and prosecuted.
Sarcastic remark, yes, but not all that far from reality.