The incident was reported around 8.45 PM yesterday, when Ashish (24), his son Raghav (3) and mother Shakuntala Devi (54) were heading on a motorbike towards Safdarjung Hospital to meet a relative admitted there.
When they were moving down the slope of the Motibagh flyover, a speeding DTC bus allegedly hit them from behind and crushed them to death, said a police official.
Passers-by called up the police and rushed them to hospital, where Ashish and Shakuntala Devi were declared brought dead.
The driver of the low-floor DTC bus - reported to be operating on the 623 route between Vasant Vihar and Shahdara - was held by the locals and handed over to the police.
More From This Section
Agitated locals pelted stones on the bus, which has been impounded by the police, said the official.
An FIR under Sections 279 (rash driving) and 304A (causing death by negligence) of IPC was registered at RK Puram police station and the driver, identified as Dalwant Singh, was arrested immediately, said the official.
Shakuntala Devi, who was pillion riding, died on the spot while Ashish and Raghav were still breathing while they were rushed to Safdarjung Hospital, eyewitnesses told the police.
They were residents of Janakpuri in west Delhi and had left home around 8 PM to meet a relative admitted at Safdarjung Hospital, the official added.