Marines are investigating after a 155mm artillery round exploded over Interstate 5, hitting California Highway Patrol vehicles with shrapnel.
Nicholas Slayton Task & Purpose
Published Oct 19, 2025 6:29 PM EDT
The Marine Corps is investigating reports that one of its artillery shells fired in yesterday’s celebrations at Camp Pendleton prematurely detonated over Interstate 5, sending shrapnel down onto the freeway and highway patrol vehicles.
The New York Times first reported on the incident, citing a California Highway Patrol report. According to the report, officers reported pieces of shrapnel raining down and hitting a California Highway Patrol motorcycle and car, as well as the ground around them. Two officers reported that a two-inch piece of shrapnel left a dent in the patrol car.
The Marine Corps is aware of a “report of a possible airborne detonation of a 155mm artillery round outside the designated impact area,” Capt Gregory Dreibelbis, a spokesperson for I Marine Expeditionary Force, said in a statement to Task & Purpose. Firing was suspended shortly after, and the Marine Corps is investigating, he said.
The Marine Corps is aware of a “report of a possible airborne detonation of a 155mm artillery round outside the designated impact area,” Capt Gregory Dreibelbis, a spokesperson for I Marine Expeditionary Force, said in a statement to Task & Purpose. Firing was suspended shortly after, and the Marine Corps is investigating, he said.
“This was an unusual and concerning situation,” California Highway Patrol Border Division Chief Tony Coronado said in a statement. “It is highly uncommon for any live-fire or explosive training activity to occur over an active freeway. 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.”
California Highway Patrol’s statement included a photo of the debris.
California Gov. Gavin Newsom ordered the stretch of Interstate 5 — which runs along the coast and has more than 80,000 people pass through it in the journey between Los Angeles and San Diego — closed for four hours while the Marine Corps’ event took place. The closure was ordered both due to the direct risk of explosive rounds being fired over the freeway and of the potential for drivers to be distracted or startled by the sound of explosions, Newsom said.
The Marine Corps had confirmed it did not request the freeway be closed, and said on Oct. 15 ahead of the demonstration that it had “conducted a detailed risk assessment. All participants will be briefed, medical, fire, and emergency assets will be on site, and multiple rehearsals will be conducted. All air, surface, and ground movements are scripted and rehearsed in accordance with standard operating procedures and established safety checklists.”
This is a developing story.