Several Afghan and US-led coalition service members were killed Monday in the latest suspected insider attack on the international military force, NATO said.
Afghan officials said the incident took place in Wardak, a flashpoint province for Taliban violence on the doorstep of Kabul, which Afghan President Hamid Karzai last month demanded US special forces leave.
"Today one or several individuals wearing an ANSF (Afghan National Security Force) uniform turned his or their weapon at a group of Afghan... and coalition service members and killed several on both sides," a NATO spokesman told AFP.
The spokesman did not give details but a government spokesman in Wardak told AFP the incident had happened there and authorities were investigating.
Interior ministry spokesman Sediq Sediqqi confirmed the location as Jalrez in Wardak and said a delegation had been sent from Kabul to investigate.
The incidents comes after the end of a two-week ultimatum by Karzai to remove a US-operated elite force from the troubled province because the Afghan leader said they were fuelling "insecurity and instability" there.