Police said Sub Inspector Rishi Pal has been arrested and a case under 304 (A) of IPC (culpable homicide not amounting to murder) has been slapped against him.
The incident took place a day after a policeman was sacked and arrested for hitting a woman with a brick.
The deceased have been identified as Shakuntala (55), Meera (50) and Maya (28). Pal was currently posted with PCR Command at the police headquarters.
"We have registered a case under section 304 (A) and the sub inspector has been arrested," said a senior police official.
Eyewitnesses said that all three died on the spot.
Pal had night duty at PHQ and was returning home when the incident took place. It is being suspected that he dozed off and lost control over the car when the incident took place.
