A 12-year-old boy is under investigation for murder after he allegedly found his father's gun in a bag at home and used it to shoot his three-year-old brother in Makgeng village, Polokwane, over the weekend.The incident took place on Saturday.In a statement, the South African Police Service (SAPS) said the boy's father was not at home but that his mother heard the gunshot."The [boy] managed to access the firearm and somehow shot his younger brother. The mother was allegedly alerted by the gunshot sound and rushed to investigate. She then realised that the worst had happened," police said.The child was rushed to a local clinic but died on arrival.According to police, the father was a former security guard.Police have confiscated the gun.Appropriate steps must be taken against the father for keeping the firearm in contravention of the Firearms Control Act, provincial police commissioner Lieutenant General Nneke Ledwaba said. "I urge all lawful firearm owners to, at all times keep them in the locked safes to avoid unauthorised access," Ledwaba said. The boy will go through processes that govern how children who are in conflict of the law are dealt with, police said, adding that probation officers had been called in to take the process forward while the investigation continues.