<span style="color: #222222;">Two American troops were killed and six others wounded when an Afghan soldier armed with a machine gun opened fire. The US military confirmed today that the incident occurred yesterday in Nangarhar province in eastern Afghanistan when US and Afghan commandos were conducting a key-leader engagement at a base in Sherzad district.<br />''<br />''Provincial governor Shah Mahmood Meyakil said in an audio message to reporters that three Afghan commandos were wounded.<br />''He said it was not immediately clear if the incident was a deliberate act by an infiltrator or an accident.<br />''<br />''In a tweet, the US Army's 7th Special Forces Group (Airborne) said several of its soldiers had been killed or injured during combat operations in Afghanistan.<br />''<br />''No group has immediately claimed responsibility.</span><br />