On November 3, the girl was invited by a woman acquaintance at her residence in Bajida Jatan area of the district, police said.
She was allegedly raped by two men at the house, police said, adding that later a youth took her to a deserted place near railway line and 11 men took turn to rape the minor.
After the incident the youth was taking the girl to a nearby railway station when Government Railway Police personnel spotted and questioned them.
Meanwhile, the youth gave a slip to the GRP, police said.
Following the incident, several raids were carried out and 13 accused were arrested, a police spokesman said.
"While six accused were arrested last evening, seven were arrested today. Till now 13 accused including the woman have been arrested," the spokesman said, adding that two more accused were still at large.