A police chief says gunmen have killed eight officers at a checkpoint in southern Afghanistan. Kandahar's police chief Sumanwal Matiullah says the gunmen threw a grenade at the checkpoint before spraying the policemen with gunfire. Matiullah says the attack happened in Kandahar's Panjwayi district late Thursday. One officer was also wounded and two others are missing. The area is known as a base for Taliban militants. Last year, more than 8,000 people were killed in insurgency-related attacks in Afghanistan - the most since the 2001 US-led invasion. Violence has claimed more than 1,700 lives so far this year.