NATO offered few details about the shooting in Afghanistan's southern Helmand province, which appeared to be the latest so-called "insider attack" to target foreign troops or contractors in the country. Afghan officials said they had no immediate details about the attack.
In a statement, NATO said the two men in Afghan uniforms opened fire on a vehicle with international troops inside it. Both shooters were killed when NATO forces returned fire, it said.
The motive for the attack was not immediately known and no group claimed responsibility for the assault. In past attacks, Taliban insurgents have been known to wear Afghan police or military uniforms to stage attacks on the international troops.
Others have opened fire apparently on the own accord, like an Afghan soldier who last year killed Maj Gen Harold J Greene, the highest-ranked US officer to be slain in combat since 1970 in the Vietnam War.
In April, an American soldier was killed by an Afghan soldier inside the compound of the governor of eastern Nangarhar province's city of Jalalabad.