Observing what I believe is criminal behavior?

I live in a large apartment complex and directly across from the seldom used tennis court. Recently very late at night I have observed a group of males use the tennis court to play various games and make noise. I can only assume that his behavior was reported to the Apartment Managers as a chain and lock was placed on the chain link door to the court. Tonight around 9:30pm my brother and I noted the courts bright lights were on and poked our heads out to see what was going on. We observed two males attempting to remove the chain or lock with a pair of pliers for several minutes. Now, while I don't see this necessarily as criminal behavior per say, its obvious that the company that runs the apartments does not want anyone on the tennis court for whatever reason and nothing says "stay out" like a chain and lock. So, these individuals are displaying their willingness to destroy property that is not theirs to get what they want. In a sense I see this as a precursor to more excessive behavior. What is to stop them from breaking into cars or even apartments. I don't even know if these persons live in my complex. Should I call the police if I see this again? That is my rather long winded question.