Both the accused have been arrested.
A food vendor, identified as Vicky (24), intercepted the 15-year-old victim near Kalwa naka on Tuesday evening, Kalwa police station sub-inspector Sachin Ambre said.
He took the girl near his house and molested her there, Ambre said quoting a complaint filed by the victim's parents.
Thereafter, tempo driver Vijay Gupta (27) also reached there and allegedly molested her, he said.
Later, when her 16-year-old sister reached there, Vicky took her to Thane's Mumbra township and allegedly molested her.
More From This Section
The victims and the accused apparently knew each other as they all reside in the same area of Kalwa.
Subsequently, their parents registered a police complaint based on which the two men were arrested last evening, the police officer said.
The accused have been booked under sections 354 (molestation) and 363 (kidnapping) of the IPC and also section 8 of the Protection of Children from Sexual Offences Act.