WASHINGTON, Sept. 5 (Xinhua) -- The U.S. Department of Defense on Wednesday announced the death of an American soldier who had been supporting Operation Freedom's Sentinel in Afghanistan, the second identified in two days.

In a statement, the Pentagon said that "Staff Sgt. Diobanjo S. Sanagustin, 32, from National City, California, died Sept. 4, 2018, from a non-combat related injury at Bagram Air Field, Afghanistan."

"The incident is under investigation," the Pentagon said.

Earlier on Tuesday, the Department of Defense said that Command Sgt. Maj. Timothy A. Bolyard had been killed. He was also supporting Operation Freedom's Sentinel in Afghanistan.

The U.S. forces in the Asian country said on Monday in a statement that an American soldier was killed and another wounded earlier on the same day in an "apparent insider attack" in eastern Afghanistan.