Zia Durrani, spokesman for the provincial police, said today the rogue policeman was shot dead by another officer.
He says the shootings took place in the Zhari district late yesterday.
It is the latest in a string of recent insider attacks in Afghanistan. Last month a rogue cop in Uruzgan province shot dead 10 colleagues.
The Taliban claimed responsibility for the attack.
The Taliban consider Kandahar their heartland, along with neighboring Helmand where poppy production accounts for most of the world's heroin.