One U.S. service member died and two others were wounded during operations in southern Afghanistan on Tuesday, the Pentagon said.
The Department of Defense did not name the casualties, saying only that the incident took place near Marjah in Helmand Province.
"We are deeply saddened by this loss," U.S. Brig. Gen. Wilson Shoffner said in a statement.
American defense officials told NBC News that U.S. Special Operations Forces were involved in a counter-terrorism operation in the Marjah area of Helmand province when they came under attack.
A U.S. medevac chopper called in to recover casualties then came under mortar and small-arms fire. the officials said. It was not clear if the helicopter had been hit by enemy fire or whether any casualties were sustained in that landing zone, the officials added, speaking on condition of anonymity.
U.S.-backed forces have been fighting to suppress the Taliban in Marjah for weeks. A spokesman for the Taliban — which frequently exaggerates its claims — said Tuesday the group had shot down a U.S. transport helicopter in Helmand.
In early December, insurgents launched a major offensive to take control of key districts in Helmand, a longstanding Taliban stronghold and the source of most of the opium that helps fund the movement.
This story originally appeared on NBCNews.com