The incident took place this afternoon at North Avenue when head constable Suresh Chand, who was posted at Rashtrapati Bhavan security, was heading to work on his motorcycle, police said.
The PCR van was also heading to an accident spot from where it had received a call about a collision between a tractor and a car.
According to an eyewitness, the speeding PCR van hit Chand's motorcycle from behind while attempting to overtake it, and claimed that the impact was such that the victim and his motorcycle skid for over 50 metres before coming to a stop.
Meanwhile, another PCR van was sent to attend to the original accident call.