[Elle Bee]

This isn't random this is organized ... I'm sure there are more

Long Island Beach Riot

Why was North Avenue Beach really closed? [Gang violence/Flash Mobs in Chicago]

Vandals Destroy Bucks County Park Facilities, Causing $Thousands In Damage

Caught On Tape: Miami Beach Shooting - Memorial Day Weekend 2011

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[Think free or die]

"This isn't random this is organized ... I'm sure there are more "

In this case, I doubt it's related to the other Memorial Day violence. If you knew the area you'd understand. It just isn't near the kinds of urban centers where you'd expect flash mobs, and it's hard to imagine a bunch of Philadelphia ne'er-do-wells deciding to pile into cars to vandalize a restroom in a Bucks County park. Too much work.