Freeway signs warn drivers on Interstate 8 approaching Interstate 5 of "Live Weapons Over Freeway" in San Diego, California, on October 18, 2025. Patrick Fallon/AFP/Getty Images

The US Marine Corps is no stranger to firing live ordnance as part of training, but it had been years — more than 70, according to one US official — since Marines had fired artillery over a stretch of the I-5 interstate in California like troops did last weekend during the Corps’ 250th birthday celebration.

The very first shell fired as part of the demonstration exploded on Saturday over the interstate, stretches of which serve as the busiest highway in America , dropping at least one shell fragment on a parked California Highway Patrol cruiser. The celebration at Camp Pendleton, California, was attended by V

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