Bullying: Out of control

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Earlier this week I discovered that, Phoebe Prince, a fifteen yr old girl, committed suicide after being continuously bullied at school for three months. Six kids were named and charged with felonies and three face juvenile charges.
Initially, when I heard this I wasn't sure to what extent she was bullied. Decades ago, bullying was a mild temperament, rarely talked about except in films. However, it's nothing compared to how children are being treated today. in addition Phoebe prince had transferred form Ireland so she was in an entirely new to the country and this is how she's welcomed?
Apparently the bullying started after she ended a brief relationship with one of the football players and that's when everyone started to gang up on her. on top of the verbal harassment there was physical abuse involved.
what bothers me the most is that none of the faculty or administration paid any attention to this behavior. some knew about the hazing that went on and did nothing to stop it.
my question is , to what extent should people be socially responsible for each other?? Because to witness something like this happening and then doing nothing about it, is just as bad as committing the crime.