Two US soldiers were killed after a man in Afghan army uniform opened fire in Nangarhar province in eastern Afghanistan.
According to a statement by the US military, six others were wounded in the attack.
The authorities said the incident happened after a joint force of Afghan and US military completed a “key-leader engagement” at a base in Sherzad district.
The individual opened fire using a machine gun, killing the US Army’s 7th Special Forces Group soldiers.
The motive of the attack was not immediately established.
Provincial governor Shah Mahmood Meyakhil said it was not immediately clear if the incident was a deliberate act by an “infiltrator” or an accident.
No group has claimed responsibility for the deadly attack.