The Marine Corps has opened an investigation after shrapnel from a 155mm artillery shell struck a California Highway Patrol (CHP) vehicle during a live-fire demonstration at Camp Pendleton.

The round reportedly detonated prematurely in the air during Saturday’s 250th Marine Corps anniversary celebration, which had been promoted by the White House.

No one was injured, but a CHP patrol car was damaged while officers were helping divert traffic on Interstate 5.

CHP officials called the incident “unusual and concerning,” noting that live-fire training rarely occurs near active highways.

Marine officials confirmed that an artillery round may have exploded outside the designated impact area and said all safety protocols had been followed.

Photos from the CHP showed shrapnel damage to the vehicle’s hood and fragments found nearby.

Governor Gavin Newsom criticized the event as dangerous and reckless, arguing that firing live munitions near an interstate could have killed someone.

The celebration, attended by Vice President JD Vance and Defense Secretary Pete Hegseth, had already drawn Newsom’s objections over safety and traffic closures, NBC News has reported.

The Trump administration defended the demonstration, calling it a standard and safe Marine Corps exercise.

Both the CHP and Marine Corps said they will review the incident to improve safety and coordination in future events.