Apparently the Chicago police know but people have said that most likely nothing will happen because this an everyday occurrence. Eye opening to say the least.
Just a warning - This video is pretty graphic. For an mmochamp thread atleast.
Edit - Just to clarify, Ive heard rumors of this being over cell phones. The Asian kid, who they think is an exchange student at the university of chicago, told security the boys were stealing cell phones from somewhere.
Never underestimate the power of stupid people in large numbers. All trying to be hard little thugs. Sad but its happens everywhere, Chicago is not the nicest place. You can YouTube Chicago Fights and probably find a dozen similar.