A helicopter crashed in northern Iraq on Wednesday, killing all 14 U.S. soldiers aboard, the military was quoted as saying by The Associated Press. The UH-60 Black Hawk helicopter was carrying four crew members and 10 passengers when it went down during a night-time operation, according to a statement. The military said initial indications showed the aircraft experienced a mechanical problem and there were no indications of hostile fire, but the cause was still under investigation. The 14 soldiers killed were assigned to Task Force Lightning, the military said.