The U.S. Marine Corps publicly identified Friday a 21-year-old service member who lost his life this week to a training accident at Camp Pendleton.

USMC Pfc. Tanner F. Rubio was fatally injured Wednesday afternoon in an accident involving a tactical vehicle, according to 1st Marine Division public affairs.

Rubio, a native of the Northern California city of Dixon, was an infantry rifleman assigned to 1st Battalion, 1st Marine Regiment, 1st Marine Division. He joined the Marines in January.

The cause of the accident is under investigation, according to USMC officials.

“The tragic loss of Pfc. Rubio is one felt across the 1st Marine Division,” said Maj. Gen. Thomas Savage, commanding general of the division. “He will be sorely missed, but his honorable service to his country will not be forgotten.”

The USMC said the accident did not occur during Exercise Steel Knight 25, a two-week-long annual training exercise aimed at strengthening the Navy-Marine Corps team and Marine Air-Ground Task Force team’s readiness. This year’s event is being held through Dec. 14 at various locations across California and Arizona, according to the Marines.