KABUL: Three police constables were killed when one of their colleagues turned his gun against them in Afghanistan's Badghis province, the latest in a string of insider attacks, an official confirmed on Sunday. The incident occurred at a police checkpoint in Muqur district, in the north of the provincial capital Qala-e-Naw on Saturday evening, deputy provincial police chief Khwaja Murad Khan told Xinhua news agency. (IANS)