A 16-year-old boy was arrested after he allegedly shot and killed his grandfather with a pellet gun in their Dullstroom home in Mpumalanga on Sunday.According to the police, the teenager got into a heated argument with his 63-year-old grandfather which led to him retrieving a firearm from his grandfather's room.After fetching the firearm, which the police described as being a pellet gun, the teenager shot his grandfather."The pensioner fell down, motionless," spokesperson Brigadier Leonard Hlathi said.The police were called to the scene by a member of the public and on arrival with paramedics, it was found the grandfather had already died. He was declared dead on the scene by medical personnel."A preliminary investigation found the man had a gunshot wound to his upper body and the boy was immediately charged for the old man's murder."The firearm has been taken for ballistic testing," said Hlathi.A pellet gun propels small metallic pellets, rather than a bullet, by using a compressed spring or air rather than gunpowder.Hlathi said the police were working together with probation offices on the case and the docket would be handed over to the Director of Public Prosecution for a decision.The teenager is expected to appear in court soon.Mpumalanga police commissioner Lieutenant General Mondli Zuma, said the law should take its course in this case.