A gunman dressed as an Afghan border policeman has killed six Nato troops during a training exercise in the east of the country.
The man was killed in the shoot-out, Nato said, but did not give any further details.
Nato did not identify the nationalities of the victims. Most forces in eastern Afghanistan are American.
The incident occurred in Pachir Wagam district of eastern Nangarhar province.
It was not immediately clear if the gunman was a police officer or someone who had infiltrated the training session. In the past, insurgents have donned police or army uniforms to attack Afghan government installations.
There have also been a number of incidents this year in which Afghan police officers turned on their trainers in deadly shoot-outs.