Four people have been arrested, one as young as 11 years old in the flash-mob attacks in Center City Friday night.
Police say the calls started coming in just after 9:00pm about thefts, muggings and physical assaults.
Two men were assaulted by the mob, one at Walnut and Juniper, the other at 15th and Locust. Both men were treated and released from area hospitals.
The swarm numbered 20 to 40 young people. The suspects range in ages from 11 to 19 years old.
All are being charged with robbery, theft and assault charges.