Three American contractors and an Afghan national were shot to death in the North Kabul International Airport Thursday, a U.S. official confirmed.
It was not immediately clear who did the shooting or whether the shooter was a member of the Afghan security forces.
The incident occurred about 6:40 p.m., the official said, adding, “this incident is under investigation.”
There has been a recent rise in so-called “insider attacks” in Afghanistan. The U.S. combat mission there ended last year.
Fox News' Lucas Tomlinson and The Associated Press contributed to this report