JALALABAD: Two US army soldiers were killed and two others wounded after an Afghan solider opened fire on coalition forces in eastern Afghan province of Nangarhar on Saturday, a local official said. “The incident took place in Achin district and the Afghan army commando involved in the firing was also shot dead after attacking the US soldiers,” Ataullah Khogyani, the provincial governor spokesman, told Xinhua. The motive behind the attack remained unknown and an investigation was launched into the incident. Insider attacks had frequently happened in the past, when an Afghan solider or policeman fires on foreign forces, causing casualties. Three US soldiers were wounded after being shot by an Afghan soldier in a base in Helmand province on March 19. The Achin district has been the scene of heavy clashes between security forces and militants of the Islamic State (IS) group over the past two years.