U.S. soldiers injured after Afghan police officer fires at NATO convoy

The NATO troops fired back, killing the Afghan Civil Order Police officer, in what has been described as a "green on blue" attack, in which a member of the Afghan forces attacks a member of a friendly force.

"The attacker was killed by return fire from Resolute Support forces," Col. Sonny Leggett of U.S. Forces-Afghanistan said in a tweet Monday.

A U.S. Forces-Afghanistan spokesman later confirmed that those injured were Americans involved in NATO's Resolute Support mission.

"We are reviewing the incident with our Afghan security partners," a NATO statement said. "Resolute Support continuously assesses force protection measures and we adapt and adjust based on the environment."

The attack came two months after another green-on-blue attack in Afghanistan's Uruzgan province, in which two soldiers of the U.S. Army's 82nd Airborne Division.