The incident took place on Saturday night in Sherzad district, reports TOLO News
US forces spokesman Col. Sonny Leggett said in a statement on Saturday night: "Upon completing a key-leader engagement at the district centre, current reports indicate an individual in an Afghan uniform opened fire on the combined US and Afghan force with a machine gun."
Leggett also confirmed that six US troopers were also injured in the shooting.
He said that an investigation was underway to determine the motive behind the attack, adding:"In accordance with US Department of Defense policy, the names of the service members killed in action will be withheld until 24 hours after notification of next of kin is complete."
In a Facebook post, Nangarhar Governor Shah Mahmood Miakhel said: "(Afghan) Army Special Forces and Resolute Support troops entered into the district. When they entered someone started shooting at them. He was killed in response.
"Three (Afghan) commandos were injured in the shooting. And a number of RS (Resolute Support) troops were also wounded."