I would not interfere, for one thing the way I see things is that if conflict is going on and you don't know how it started you should let the two parties solve it. Of course If I knew both people I would probably break up the bullying but that is really all I can do,I mean the bully might just come right back, or even worse start butt-fucking me for interrupting
I don't blame the people for not helping people these days for some reason have guns and the need for blood. Crazy man...