Tulja Kapure was attending a nature's call on the road near Ambedkar Nagar 2 of Tilak Nagar where she resided when the incident took place, they said.
"R N Gandhi school is located opposite Ambedkar Nagar. At about 7.30 AM, the driver of the bus was taking a turn and did not see the girl, who was crushed under rear wheels of the vehicle," said R M Gavit, senior inspector at Tilak Nagar police station.
The victim, who sustained severe injuries, died on the spot, police said, adding the body was taken to nearby Rajawadi hospital for postmortem.
The 43-year-old driver of the school bus, identified as V Moniwannan was later arrested on the charges of causing death of a person due to negligent driving, police said, adding they have taken his blood samples to ascertain if he was under the influence of alcohol.
The verification was also on to ascertain if the bus is owned by the school or it hired the vehicle to ferry students, police said.