From msn.com:
The Marine Corps has begun an investigation into how an artillery shell exploded over Interstate 5 in California, raining down pieces of shrapnel as Vice President JD Vance and other top U.S. officials observed a military demonstration and supercharging a spat between the Trump administration and the state’s Democratic governor.
The shell was one of six launched Saturday from an M777 howitzer on a beach at Camp Pendleton, a major military installation bisected by the interstate, two defense officials said, speaking on the condition of anonymity because of the issue’s sensitivity. The most likely cause for the detonation was a fuze failure — something Marine Corps leaders saw as a “one-in-a-million” possibility before it occurred, the officials said.