The U.S. military’s death count in the war in Afghanistan has hit 2,000 as a U.S. soldier and a contractor were killed in a checkpoint shooting in eastern Afghanistan, the BBC reported citing U.S. officials.

The shooting, which occurred in the eastern Wardak province on Saturday, also resulted in three Afghan soldiers being killed and several injured.

The International Security Assistance Force (ISAF) initially said the soldier had probably been killed by the Afghan security services, but it later said the circumstances were vague.

Over 50 foreign soldiers and officers have been killed by Afghan police officers and servicemen in so-called green-on-blue attacks since the start of the year and the international coalition in Afghanistan has lost more than 330 troops killed so far in 2012, according to ISAF information.

The foreign troop contingents are scheduled to withdraw by the end of 2014 and the NATO-led coalition plans to hand over responsibility for security in Afghanistan to the Afghan leadership by that time.