(NBC) - by COURTNEY KUBE and AHMED MENGLI
Three U.S. soldiers were killed and one other was wounded Saturday in eastern Afghanistan when an Afghan soldier opened fire on them, U.S. officials confirmed to NBC News.
The shooter — identified as a member of the Afghan National Army's Commando Forces — was killed in return fire, officials added.
The incident occurred during a joint U.S.-Afghan military operation in the Achin district of Nangarhar province, according to the provincial governor's spokesperson.
The wounded U.S. soldier was evacuated for medical treatment, the Pentagon said in a statement Saturday, without further detail of the injuries.
Officials said the Americans were killed in an apparent insider, or so-called "green-on-blue," attack by an Afghan ally soldier on U.S. service members.
Their identities were not immediately released and the incident remained under investigation, officials said.
President Donald Trump was briefed on the "emerging situation" in Afghanistan, White House deputy communications director Raj Shah said earlier Saturday.
The attack follows one in March in which three American soldiers were shot and wounded by an Afghan soldier on a base in Helmand province, officials said. That Afghan soldier was also killed following the incident.