U.S. service member killed, two injured in Afghanistan insider attack

July 7 (UPI) -- One U.S. service member was killed and two injured Saturday during an apparent insider attack in southern Afghanistan, a NATO-led mission release said.

The injured service members were in stable condition and undergoing treatment, the statement from NATO Resolute Support, a North Atlantic Treaty Organization-led, non-combat mission said.

The U.S. soldiers were not identified. The release of the name of the service member killed in action is being withheld until 24 hours after next of kin notification is complete, the release said.

The incident is being investigated.

An insider attack is when a member of the Afghan National Security Forces, who U.S. military personnel are advising and training, attacks a U.S. service member, a Military.com report said.

Insider attacks have taken place every year since 2008 and the Afghan province of Helmand, a Taliban stronghold to the south and center of the country's opium-growing industry, has seen the most attacks.