One US serviceman was killed and another was injured after an AH-64 Apache attack helicopter crashed shortly after takeoff from an airfield in Kandahar in southern Afghanistan, officials said.
The military has ruled out hostile fire as the cause of the crash on Sunday, which is under investigation.
"We deeply regret the death of our superb pilot tonight," Army Major General Benjamin Freakley, commander of Combined Joint Task Force 76, said in a statement on Sunday.
"Our thoughts and prayers are with the family, friends and fellow aviators of our dedicated soldier who lost his life tonight executing a mission he believed in. His sacrifice will not be forgotten."
The helicopter was responding to a reported rocket attack against Kandahar airfield when it went down, the officials said.