The incident occurred near Azimchak under Gaurichak police station here.
"All the victims were identified as residents of Jehanabad district," police said.
Hundreds of people, angered by the incident, gathered on the Gaya-Masaurih Highway in protest, blocking the road and demanding action against the owner of the car.
Witnesses said that the two people in the car parked it at the side of the road and fled. Police have seized the car and begun investigations.