A NATO helicopter has crashed into a house on the outskirts of Kabul, killing 12 Turkish soldiers on board and four civilians on the ground.
It was the worst loss of life in Turkey's 10-year involvement in Afghanistan. One Afghan civilian was also injured.
"The helicopter crashed into a house in Bagrami district of Kabul due to technical problems," a senior Afghan police officer told the Reuters news agency on Friday.
There was no immediate comment on the crash from Turkey, which has more than 1,800 soldiers serving in Afghanistan, most of them around the capital.
Prior to Friday's crash, Turkey had lost only two soldiers who died in a car crash in 2009.
The crash came amid growing unease among NATO partner countries about the increasingly unpopular and costly war. Most foreign combat troops are set to leave Afghanistan by the end of 2014.
Unlike other European members of the NATO-led coalition, Turkey's mission is limited to patrols and its soldiers do not take part in combat operations.
In January, six US Marines were killed in a helicopter crash in southern Afghanistan, which followed the deaths in August of 30 American personnel, including 22 Navy SEAL commandos, in a crash in the east.
An investigation into the August incident confirmed the Taliban had fired a rocket-propelled grenade that hit one of the
rotary blades and exploded, sending the helicopter plunging down and bursting into flames.