Two American soldiers were killed, six were injured in the shooting in Afghanistan, Reuters reported.

The incident occurred in Nanganhar province when Afghan and US troops were returning from the event, said US Air Force spokesman for Afghanistan, Colonel Sonny Leggett.

"Current reports indicate an individual in an Afghan uniform opened fire on the combined U.S. and Afghan force with a machine gun," he said. "We are still collecting information and the cause or motive behind the attack is unknown at this time."