The Secretary-General of the United Nations Ban Ki-moon has expressed sadness over the crash of a helicopter on Friday in the outskirts of Afghanistan's capital city of Kabul, killing 12 Turkish troops and two Afghan women. A spokesman for Ban Ki-moon said the Secretary-General expressed his deep sympathies with the families of the victims and expressed his condolences to the Governments of Afghanistan and Turkey. The helicopter, which belonged to International Security Assistance Force (ISAF) in Afghanistan, crashed into a house yesterday, killing 12 Turkish soldiers and two Afghan women. The Turkish government suggested that the cause of the accident was a mechanical failure.