A U.S. Marine died during a training exercise Wednesday at Camp Pendleton, military officials said.

The Marine died of injuries sustained in a “tactical vehicle mishap” in the afternoon, the I Marine Expeditionary Force said in a statement.

The Marine’s name was not released, and the cause of the incident was under investigation.

No further details were given.

The I Marine Expeditionary Force is the largest of the three Marine expeditionary forces and is located on the coast in San Diego County.