By Jim Hilgen
http://stream.publicbroadcasting.net/production/mp3/wrti/local-wrti-894363.mp3
"Flash Mobs" in Philadelphia: Groups of Young People Converging in the City Have Turned Violent
Philadelphia, PA – "Flash mob" activities in Philadelphia have increasingly turned into violent affairs, frightening visitors and merchants, and drawing stern rebukes from city leaders. WRTI's Jim Hilgen looks at how these social network-driven events started, and measures authorities are taking to combat them in the future.