Johannesburg - An off-duty police officer shot dead two people and wounded another in Meadowlands, Johannesburg, before turning the gun on himself, Gauteng police said on Tuesday."He shot and killed his girlfriend, the girl's mother, and also injured a tenant," said spokesperson Mack Mngomezulu."After that he shot himself and died on the scene."The incident happened at the constable's girlfriend's house in Zone Eight around 18:00 on Monday.All three died on the scene. The tenant was taken to hospital.The constable's official firearm was found on the scene."The motive is unknown. Police are investigating murder, attempted murder, and an inquest case was opened," said Mngomezulu.