The fact that these disturbances were not reported in the media is strong evidence that it was racially motivated.
Mere “hooliganism” would have created more headlines.
And in Philly (among other racially motivated crimes), this:
Group Of Teens Randomly Attack Man On Kelly Drive
http://philadelphia.cbslocal.com/2011/08/09/third-flash-mob-attack-reported/
Philadelphia Mayor Michael Nutter has announced a curfew for specific areas of Philadelphia on Fridays and Saturdays in order to curb the recent spread of dangerous flash-mobs in the city. “Today, we are issuing an enforcement response and a community response to these terrible acts by a small number of reckless teenagers who have damaged our city and our citizens,” Nutter said.
The dangerous flash-mobs have been involved in violent incidents in the past. Recently, two men were attacked in Philadelphia’s Center City district by a flash-mob of 40 people. In another flash-mob incident, a cyclist was beaten in Philadelphia’s South Street neighborhood in 2009 after a flash-mob formed in the area. Nutter and other city officials hope that the curfew will keep such incidents at bay during the summer months.