An Afghan army soldier opened fire at NATO forces in southern Afghanistan’s Kandahar province, killing a US serviceman and an Afghan interpreter, the Tolo TV station said on Friday. The soldier, armed with a machine-gun, climbed at a building roof and started shooting, killing two people. Three US servicemen were injured in the shooting. The attacker was killed when ISAF forces returned fire. This is 11th similar incident in Afghanistan this year. A total of 18 international coalition servicemen were killed in 2012. According to media reports, some 80 servicemen of the NATO-led International Security Assistance Force were killed by Afghan army, police and intelligence personnel since 2007. About 75 percent of all such attacks took place in 2011 and 2012, according to the Department of Defence.