An Afghan soldier opened fire at Camp Shorab air base in southern Afghanistan, wounding three US soldiers before being shot dead.
The injured American troopers are receiving medical treatment, the NATO-led Resolute Support mission said.
Afghan military spokesman, Rasoul Zazai, told Reuters that the incident happened at 3 p.m. local time Sunday at Camp Shorab in the Afghan province of Helmand.
An Afghan special forces operative “lost his life in exchange of fire” after wounding three US soldiers, he said.
According to AP, Zazai claimed the Afghan soldier’s actions weren’t deliberate and that he just made a “mistake.”
Insider attacks by Afghan soldiers, once a major security concern, have been on the decline recently due to improved security at bases, and the withdrawal of most of the international contingent from Afghanistan in late 2014.
Currently, around 13,000 foreign troops remain in the country as advisers and instructors for the local security forces fighting the Taliban.
In October 2016, an Afghan man dressed in a military uniform shot dead a US serviceman and an American civilian contractor at a military base in Kabul.
Two Romanian soldiers were shot dead and one wounded last May after Afghan police officers they were training, opened fire on them.