A U.S. Army soldier from Tennessee was killed Monday during combat operations in Afghanistan, the U.S. Defense Department confirmed Tuesday.

Sgt. 1st Class Jeremy W. Griffin, 40, from Greenbrier, Tennessee, was killed by small arms fire when his unit was engaged in combat operations in Wardak Province, Afghanistan.

The incident is under investigation, the DOD reported.

Griffin was assigned to 3rd Battalion, 1st Special Forces Group (Airborne), Joint Base Lewis-McChord, Washington.

“The loss of Sgt. 1st Class Griffin is felt across the 1st Special Forces Group (Airborne) Family and the entire Special Forces community,” Col. Owen G. Ray, commander, 1st Special Forces Group said in a statement, to The Army Times.

“He was a warrior — an accomplished, respected and loved Special Forces Soldier that will never be forgotten. We ask that you keep his Family and teammates in your thoughts and prayers.”

Griffin was the 17th U.S. soldier killed in action in Afghanistan this year.