The detonation of a military round over the 5 Freeway during an exercise at Camp Pendleton in October was a “one in a million” malfunction that investigators have struggled to explain, according to a report from the U.S. Marine Corps released Friday.
The investigation determined the military round exploded before it was supposed to because the device’s fuze went off early, raining metal shrapnel below. A California Highway Patrol cruiser was punctured by metal.
“Of all days for this very low probability event to happen, why this one? What was different from the thousands of times before this event employing the same shell-fuze combination, weapons system, and highly trained Marines?” the report read. “There is no definitive answer to these questions.”
The incident occurred Oct. 18 during the Marine Corps’ 250th anniversary celebration, after Vice President JD Vance had been escorted to Camp Pendleton to witness the exercise. A 17-mile stretch of the freeway was stopped half an hour before the exercise was set to begin at 1:46 p.m., drawing the ire of thousands of weekend travelers.
The White House initially criticized California Gov. Gavin Newsom for shutting down the freeway during the military exercise, stating on X that “the Marines repeatedly said there are no public safety concerns.”
But after word spread of the early detonation, Newsom called on the Trump administration to apologize, saying the exercise was “reckless” and one of the White House’s “vanity projects.”
“We’re thankful to the Marines for their thorough and precise investigation — in stark contrast to the dangerous and performative demands by JD Vance and Pete Hegseth to shoot live ammunition over a civilian area for their entertainment,” said Diana Crofts-Pelayo, a spokesperson for Newsom’s office in a statement .
The White House also did not respond to a request for comment.
According to the report, there were no injuries from the falling shrapnel, but it did strike the CHP vehicle as well as a CHP motorcycle near Las Pulgas Road.
The report suggested possible causes for the premature fuze detonation but determined that military personnel were not at fault.
The shrapnel came from an M795 round that had been paired with an M767A1 fuze, which was meant to electronically detonate the round at a predetermined point, the report said.
Instead, the round detonated prematurely at 453 meters, or about 1,486 feet, in the air, around 3,300 feet from its firing location, according to the report.
The size of the shrapnel that struck the CHP vehicles was described as 2 inches by 2½ inches.
The report states that the fuze that was used in the exercise is “extremely reliable” and had only one previous recorded malfunction, in 2017.
“It is manufactured to a tolerance of one defect in a million,” the report states. “The likelihood that the M767A1 fuze malfunctioned is a statistical anomaly that was outside any reasonable probability.”
Investigators ruled out the possibility of the round striking a drone in the area and, although it was possible it might have struck a bird, noted that “none were observed along the flight path of the projectiles during the incident, and no organic residue was found on shell fragmentation.”
Instead, the report noted that the M777 Howitzers, the artillery used to fire the rounds, might have been too close to one another as they fired, or the fuze might have been exposed to “anomalous electromagnetic energy in the vicinity.”
According to the report, the positions of the Howitzers were changed three days before the event, occupying a 50-by-50-meter box that was smaller than originally planned. That meant that some guns were 10 to 15 feet apart, according to the report.
“Several career artillery officers note they have never seen howitzers placed this close together but also acknowledged that there was no restrictive minimum distance of Gun placement in relation to administrative artillery live fire,” the report reads.
The report states that investigators reached out to the United States Secret Service to ask if electronic countermeasures, or ECM — which can be used to disrupt or jam electronic systems — were used by the agency that day during the demonstration. The White House Military Office told investigators it did not take such measures.
According to the report, President Trump had been scheduled to attend the event initially but Vance was instead sent in his place.
