An Afghan policeman shot dead three U.S. advisers to the international coalition forces in Afghanistan (ISAF) at Herat airfield in the west of the country on Sunday night, Pazhwok agency reported quoting local security forces.
Another foreign adviser and an Afghan translator were also injured in the attack, and later hospitalized. The policeman was killed in return fire by airfield security guards.
ISAF confirmed the incident had taken place but could not confirm the nationality of the dead.
The attack is the latest in a string of so-called green-on-blue incidents involving attacks by Afghan security forces on ISAF staff, which have killed 27 ISAF soldiers this year. There were 35 such deaths last last year.
An Afghan army soldier on Monday shot at U.S. servicemen in the northern Faryab province, seriously injuring two.
The soldier entered the U.S. headquarters building and opened fire. He was killed in return fire.
