In total, 13 youths are now suspected of participating in the robberies, according to Expressen.
The gang is thought to have targeted fathers who are not residents in the area.
“It’s those who have the most to lose from reporting the attacks and who don’t recognise [the attackers],” said police spokesman Sven Nilsson.
The gang apparently made contact with the men via different internet chat sites and then arranged meetings with them.