A 57-year-old assistant commissioner of police (ACP) allegedly shot dead his wife and nephew with a gun before shooting himself fatally at his home in Maharashtra's Pune city on Monday, an official said.

The incident took place at around 3.30 am at ACP Bharat Gaikwad's bungalow in Baner area. The reason behind the incident was yet to be ascertained, the official from Chaturshringi police station said.

Gaikwad was posted as ACP in Amaravati and had come home, according to police.

"At around 3.30 am on Monday, the ACP first allegedly shot his wife in the head. Upon hearing the gunshot, his son and nephew came running and opened the door. The moment they opened the door, he allegedly shot at his nephew, who got hit in the chest," the official said. "Later Gaikwad shot himself in the head. All the three persons died on the spot," he said.

The other two deceased were identified as the police officer's wife Moni Gaikwad (44) and nephew Deepak (35), he said.

A probe was on into the incident, the police added.