According to Canadian laws, and the laws of many other societies, even accusing a juvenile of a criminal offense is essentially considered punishment since it will color their future regardless of whether or not they are acquitted. That is one of many reasons why we have separate legal frameworks for juvenile offenders.
So, assuming the police have one set of suspects, and they are all juveniles under the law and a lack of sufficient evidence, this is nothing more than a mob's attempt to railroad the accused.
As another commenter posted above: see how you feel about "Anonymous justice" when you are in their cross-hairs.