A U.S. military humvee guards the scene of a U.S. helicopter crash in the Shahjoi district of Zabul province in Afghanistan

Officials have ruled out enemy fire as the cause of a U.S. military helicopter crash in Afghanistan that killed eight service members and injured 14 others.

NATO spokesmen say the Chinook transport helicopter crashed after the pilot reported an unexplained loss of power and engine failure.

The helicopter went down early Sunday in southeastern Afghanistan near the main highway between Kabul and Kandahar in the Shahjoy district of Zabul province. Taleban militants are active in the region.

The U.S. military relies heavily on helicopters for transport and operations in Afghanistan because of rough terrain and a lack of roads. Dust and high altitude put a heavy toll on helicopter engines, which have to operate at maximum limits under such conditions.

Some information for this report was provided by AFP, AP and Reuters.