A Gunman wearing an Afghan army uniform opened fire on coalition troops in western Afghanistan,military authorities said late Monday. An official said several NATO troops were wounded in the shooting and the gunman was killed. NATO and Afghan authorities were investigating the shooting,which took place Saturday at an outpost in Bala Boluk district,about 700 km west of Kabul,said Afghan Defence Ministry spokesman Gen Mohammad Zahir Azimi. A NATO statement said there were no fatalities among alliance soldiers. An official who asked not to be named said several coalition troops were wounded. He said the man who opened fire was later killed by the NATO troops. If the probe confirms the gunman was a soldier,the shooting would be the latest in a series of attacks by Afghans against coalition partners. Those shootings have raised fears of Taliban infiltration as NATO speeds up the training of Afghan security forces. The expansion of the army and police is a critical element in NATOs exit strategy from Afghanistan. Coalition troops are to end their combat role in 2014,and the goal is to have 1,95,000 trained Afghan troops in service by next October. Afghan security forces have already started taking the lead in several regions as part of the process that will put them in charge of security across the nation by the end of 2014. Commanders of NATOs training mission have said that coalition and Afghan forces keep a sharp eye out for possible Taliban infiltrators at the recruitment.