In an attack described as "shocking", police said they believed the gang of men and teenagers planned the horrific rape in a well-lit park in Roxburgh Park, the Herald Sun reported.
Members of the gang followed the pair of schoolgirls from Broadmeadows train station to a McDonalds where the girls were lured to a park and repeatedly raped at around 10.30pm on October 24.
After drinking with the gang, the two girls were dragged to opposite ends of the park and raped, Detective Inspector Glenn Davies said.
"The girls were calling out to each other from either side of the park. Those calls were heard by witnesses," he said.
Police have released CCTV images of several men believed to be part of the gang of rapists responsible.