Given that this happened in Tensta, yours is an extremely likely presumption.
factoids about Tensta:
Unemployment rate: 43.5 %
Welfare rate 40.2 % (data from 1999, so it's probably higher now)
Immigrants: 66 %
95 to 100 % of all children in schools in the area are of 'foreign origin'.
I’d presume so, since I don’t remember native Swedes having an affinity for gang rape.