The charges include felony rioting, disorderly conduct and harassment. One of those juveniles has also been charged with assault on police.
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The charges stem from the incident that began at about 4 p.m. Wednesday when a large group of teens began fighting around 15th and Chestnut Streets downtown.
Concerned store owners called police and officers moved in to arrest the suspects. Police said some of the teens attempted to flee the scene by getting on Southeastern Pennsylvania Transportation Authority's Broad Street Line.
A total of 18 teenagers were arrested and they are facing disorderly conduct charges.
There were no reports of any injuries or property damage in Wednesday's incident.
Wednesday's incident comes nearly two weeks after approximately 100 teens engaged in a mob-like atmosphere
inside the Macy's Department Store located in the 1300 block of Market Street. Fourteen teens were taken into custody.
In addition, a flash mob caused extensive damage to a South Philadelphia convenience store in June 20009.
Investigators think the flash mobs are organized on social networking Web sites.
Local Video from CBS 3 in Philadelphia