The half naked victims were thrown out of the bus where several auto rickshaws, cars and bikes slowed down but no one stopped for about 25 minutes.
The passerby phoned the Delhi Police, who took the couple to Safdarjung Hospital, where the female victim was given emergency treatment and placed on mechanical ventilation.
The victim's friend rued the fact that three PCR vans arrived at the scene after about 45 minutes, but wasted time in deciding under which police station's jurisdiction the case fell.
He said nobody, including the police, gave them clothes or called an ambulance. After repeated requests, someone gave him a part of a bed sheet to cover his friend.