As a victim of such little bastards in the community, I have to say that parents MUST be held responsible for their childrens actions - if they are not making an effort to control their kids' behaviour and teach them to leave other people in peace, they should not be allowed to get away with it.
As for the kids, they also should be forced to face the consequences of their behaviour, and punished/taken into custody where appropriate. The rest of us have rights too.