One prisoner has been killed and six people including three policemen injured during a clash at a jail in southern Afghanistan, officials said. The incident took place Monday night in the city of Kandahar, the former stronghold of the ultra-Islamic Taliban regime. \"One prisoner was killed and six others including three police were injured in Kandahar prison,\" city police director General Salim Khan told AFP Tuesday, declining to give more details. The trouble started when an inmate attacked a prison police guard and opened fire, injuring him and two other policemen, a police source said. In a subsequent exchange of fire the attacker was killed and three prisoners were wounded, the source said. Interior ministry spokesman Lutfullah Mashal was not available for comment. On December 17 four guards and two prisoners were killed in Kabul\'s main jail as clashes erupted after an escape attempt. In the Kabul riot, a Pakistani and an Iraqi detainee were killed after attacking a guard at Pul-e-Charki jail with a razor blade and stealing his gun. They were killed after intervention by the national army. (AFP)