What is the deal with flash mobs in Philadelphia

I have to say that today, kids can come up with the most destructible and ignorant ways to spend their time. What is an 11 year old boy doing in the middle of the city with a group of violent people, just to end up arrested? Why are kids doing these flash mobs anyway, and why do they have to be violent? Two of them happen within several minutes of each other in the middle of the city of Philadelphia and the Mayor doesn't know what to do so far except implement a curfew for 9:00pm on the weekends. Where are these kids parents is what I want to know? If my 16 year old and especially my 11 year was arrested for violence and beating people up in a flash mob, they would never see the light of day again, except to go to school. Isn't it about time we start holding the parents responsible for their kids behavior and arrest them as well? I would have been grounded for life if I was involved in something like that when I was that age. It is just amazing that up until now at least, no one has been killed, even though several were beaten. What a waste of a young person's time! What a waste!http://philadelphia.cbslocal.com/2011/08/08/nutter-sets-9pm-weekend-curfew-for-minors-in-center-city-university-city/