NBC NEWS: KABUL - Six U.S. soldiers serving with the NATO International Security Assistance Force were killed when their Sikorsky UH-60 'Black Hawk' helicopter crashed in southern Afghanistan Tuesday, officials said.
The cause of the crash is under investigation, NATO said in a statement, but a senior U.S. defense official said the aircraft had a hard landing due to mechanical problems and was attacked by militants after it went down.
NATO did not disclose the nationalities of the victims but the U.S. official said they were American.
There were no reports of enemy fire in the area the when helicopter went down, the NATO statement added.
The helicopter crashed in the Shahjoi district of the Zabul province, according to its deputy governor Mohammad Jan Rasulyar.