A policeman was killed and another injured in accidental firing at the residence of former Congress MLA Devti Karma in Raipur, Chhattisgarh, on Friday. The two personnel of Chhattisgarh Armed Force were cleaning their service weapons in barracks when a pistol accidentally went off, sources said.Devti is the wife of Mahendra Karma, who played lead role in Salwa Judum movement & was assassinated by Maoists in the Jheeram Valley massacre.