Brigadier General William Shoffner, head of public affairs at NATO's Resolute Support base in the Afghan capital Kabul, said today that three foreign troops were also wounded in the attack.
He says the attack happened at around 1.30 PM local time in the vicinity of the base, which is the biggest US military facility in Afghanistan.
The Taliban has claimed responsibility for the attack in an email to The Associated Press.
NATO could not confirm the nationality of the dead, according to policy.