The incident took place late last night when the victims, aged around 15 years, residents of Khadegolavali of Kalyan, were returning home after attending tuition, Senior Police Inspector A V Saigaonkar of Central Police station said.
Instead of taking them home, the auto-rickshaw driver identified as Raju Dathkhile took the victims to a different area - Sapna Gardens. After this, Datkhile and his friend - Chandrakant Mhatre, who was in the auto, allegedly molested the girls.
The duo threatened them of dire consequences, including an acid attack, if they narrated the ordeal, the officer said.