Six personnel of the Indo-Tibetan Border Police (ITBP) were killed and two others injured in Chhattisgarh today after a colleague fired at them on Wednesday, the police said. The accused, a constable, then turned the gun on himself. The incident took place at around 9 am at an ITBP camp in the insurgency-hit Narayanpur district, around 350 km from state capital Raipur, said Inspector General of Police (Bastar range) Sundarraj P.