http://en.wikipedia.org/wiki/2005_civil_unrest_in_France
and London riots/flash mobs:
http://en.wikipedia.org/wiki/2011_England_riots
The European riots are only significant because they're unusual against such comparatively low levels of background violence.
http://en.wikipedia.org/wiki/2005_civil_unrest_in_France
and London riots/flash mobs:
http://en.wikipedia.org/wiki/2011_England_riots