The Marine Corps has concluded that a highly unusual artillery malfunction caused a shell to detonate over Interstate 5 during a California event last year, causing debris to hit a California Highway Patrol vehicle.
The October incident took place during a celebration marking the Marine Corps' 250th anniversary.
A newly released Marine Corps report, spanning more than 600 pages, found the mishap stemmed from a failure in the artillery shell's fuze, the electronic component that controls when the round detonates.
"The M767Al fuze is extremely reliable, with only one malfunction in its service history, in 2017, that was ultimately determined to be caused by an external factor," the report said, according to The Hill. "It is manufactured to a tolerance of one defect in a million."
According to the report, the fuze exploded midair about 1,500 feet above I-5 instead of detonating in the designated training impact area.
Investigators ruled out misconduct by Marines, as well as interference from birds or other unmanned aerial systems.
The report instead pointed to a combination of otherwise harmless conditions that may have increased the odds of a malfunction.
Those factors included the close positioning of weapons, blast overpressure, and the possible presence of an electromagnetic charge.
No injuries were reported. However, the CHP said a small piece of metal debris struck and damaged one of its vehicles while officers were handling a freeway closure at the Las Pulgas Road on-ramp to I-5 South.
The Marine Corps report said the fragment measured about 2 inches long and half an inch wide, leaving a minor dent and scratch on the vehicle's hood.
After CHP alerted the Marine Corps, additional live-fire exercises were called off.
The I-5 closure itself was also a source of debate during the event.
In the report, the Marine Corps said shutting down I-5 was initially required when President Donald Trump had been expected to attend the celebration. That requirement was later removed after Vice President JD Vance became the guest of honor.
Still, CHP and California Gov. Gavin Newsom moved forward with traffic breaks as a safety measure.
"This was an unusual and concerning situation. It is highly uncommon for any live-fire or explosive training activity to occur over an active freeway," said CHP Border Division Chief Tony Coronado.
"As a Marine myself, I have tremendous respect for our military partners, but my foremost responsibility is ensuring the safety of the people of California and the officers who protect them," Coronado added.
Although Marine Corps officials described the malfunction as extraordinarily rare, the report recommended a review of the fuze and ammunition used in the demonstration, which could result in changes for future events.
Nicole Weatherholtz ✉
Nicole Weatherholtz, a Newsmax general assignment reporter covers news, politics, and culture. She is a National Newspaper Association award-winning journalist.
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