A soldier with Afghan National Army (ANA) opened fire on NATO-led troops, killing a U.S. service member and wounding two Italian soldiers in Badghis province, northwest Afghanistan, a senior military spokesman of ANA in the region said Wednesday. 'An ANA soldier who is believed to have mental problem opened fire on international troops in Balamirghab district on Tuesday, killing a U.S. soldier and injuring two Italian troopers,' Basir Khan Ghori told Xinhua. The assailant was injured after Afghan and NATO forces returned fire, he added.He further said that the soldier had been taken to hospital and investigation is underway. A statement from NATO-led International Security Assistance Force (ISAF) also confirmed a U.S. service member died following a shooting Tuesday in western Afghanistan, adding that ISAF is investigating the incident with its Afghan partners. Regarded as the hotbed of Taliban militants in northwest Afghanistan, Balamirghab district has been the scene of skirmishes between security forces and Taliban militants over the past one year. This is the second case of its kind over the past couple of months. In the previous incident in early November, an Afghan police opened fire on British troops in Nadali district of Helmand province, killing five soldiers. 