Philly Answers Youth Flash Mobs With Curfew Enforcement
Not that it's the first city to enforce a youth curfew, and not that kids on a crime-spree is the only variety of moral panic offered as a rationale, but Philadelphia is cracking down through increased enforcement of a youth curfew law after children and teenagers attacked two people in the Center City district — attacks which, according to police, were coordinated via text messaging.
And in this case, it wasn't really a flash mob at all, it was just a gang of hoodlums.
This story doesn't seem relevant to this site at all to me.