Which ‘Eastern European’ country could gangs of Mohammedans be from? Bosnia, Albania, Russia if Chechnya is counted as Russia? I can’t imagine these are Polish converts from Catholicism doing this in Switzerland. And circumlocutions don’t really help reporting, journalists.
I doubt any of these guys are from Poland, but Poland does have a surprisingly old Muslim population: http://en.wikipedia.org/wiki/Islam_in_Poland