What to do about a fight after kids get off school bus.?

Okay, today we pulled in at the end of our road after the kids got off the school bus. My boys ride with me so they weren't there. A highschool freshman jumped on a younger boy and started beating him up. My husband stopped the fight but we won't always be there when the bus runs. My question is, what can we do about it to make the community safer for the children and to deter these youngsters from becoming thugs? The parents of the older boy won't do anything. Can the school help? The school board? The police?