Claim:

The U.S. Marines fired live ammunition over Interstate 5 in Southern California on Oct. 18, 2025, during an artillery demonstration at Camp Pendleton, causing a temporary closure of the highway.

Rating:

True

Posts claiming the U.S. Marine Corps fired live ammunition over Interstate 5 in Southern California, causing the highway to close temporarily during what the Marines called “a live-fire amphibious capabilities demonstration” at Camp Pendleton, circulated online in mid-October 2025.

Users on social media platforms such as X (archived) and Instagram (archived) posted about the closure of I-5 due to the use of live ammunition, though other users reported confusion (archived) over whether the traffic closure was due to the Camp Pendleton display or the “No Kings” protests happening across the country. 

Jim Desmond, an elected official in San Diego County, claimed (archived), “The Marines at Camp Pendleton have been firing live rounds and training beneath I-5 for over 50 years — without closing the freeway” and blamed the closure on California Gov. Gavin Newsom “to create chaos and score political points.”

Damn, King Trump is shutting down a major freeway between Los Angeles and San Diego…..to fire artillery??
…what a circus. 🎪 🤡 #i5 #interstate5 #artillery 
….
“The President is putting his ego over responsibility with this disregard for public safety. Firing live rounds… pic.twitter.com/4Jf4xV2qLr

— FCG Studio (@FCG_Studio) October 18, 2025

The claim that the Marines fired live ammunition over I-5 during a weapons demonstration at Camp Pendleton was true, as was the assertion that the display was the reason for the roadway’s temporary closure. 

CalTrans posted a notice of an “unscheduled closure of I-5 in the region of Camp Pendleton” on Oct. 18. The statement read, in part: 

Due to safety concerns, a section of Interstate 5 will be closed today, Saturday, October 18, due to a White House-directed military event at Camp Pendleton involving live ammunition being discharged over the freeway.

For public safety, a section of Interstate 5 today from Harbor Drive to Basilone Road will be closed between approximately noon until the end of the event.

CalTrans added that “passenger rail service on the adjacent rail line will also be disrupted.”

The live-fire occurred during an event celebrating the 250th anniversary of the Marines. Snopes previously reported on the strained communication between the federal and state governments leading up to the event, which led to confusion from the public about whether the highway would be closed. 

Vice President JD Vance and Defense Secretary Pete Hegseth visited the base — located in San Diego County — to “watch troops put on a show of amphibious vehicles and Marines demonstrating a beach assault,” The Associated Press reported.

As a result of the demonstration, a piece of shrapnel from ordnance that exploded prematurely struck a California Highway Patrol vehicle that was assisting with a traffic break, a representative for Newsom told Snopes via email. 

CHP released a statement about the incident on Oct. 19, stating that “metal shrapnel from explosive ordnance fired over the Interstate 5 freeway detonated overhead prematurely, striking and damaging a CHP patrol vehicle.” The department said there were no reported injuries and that “personnel immediately notified the Marine Corps at the scene, who then canceled firing additional live ordnance over the freeway, and the area was swept for further evaluation.”

Debris from a Camp Pendleton training round detonated midair over I-5, striking a CHP patrol car assisting with a traffic break. No injuries. CHP is recommending an after-action review to enhance coordination.

NEWS RELEASE HERE🔗 https://t.co/xnoKm3qLp2#CHP #newsrelease pic.twitter.com/eN0wMA46w3

— CHP Border Division (@CHP_Border) October 20, 2025

CHP Border Division Chief Tony Coronado called it “an unusual and concerning situation,” adding that “it is highly uncommon for any live-fire or explosive training activity to occur over an active freeway.”

The Marines announced plans for the demonstration on Oct. 15, which led to Newsom and the administration of President Donald Trump trading barbs. 

A primary issue appeared to be whether I-5 would close during the display. Before the event, the Marines insisted it would not require the closure of the highway. According to a statement from Newsom’s office, the Marines “confirmed their exercise would be conducted on its training ranges, as it routinely does, but not over the freeway.”

However, that appeared to change the night before the event. 

According to Newsom’s office, on the evening of Oct. 17, “the state then received notice from event organizers asking for CalTrans signage to be posted along the I-5 freeway that would read: ‘Overhead fire in progress.'” 

The statement continued: “Due to extreme life safety risk and distraction to drivers, including sudden unexpected and loud explosions, a section of I-5 will be closed for a period on Saturday, October 18. This decision comes at the recommendation of traffic safety experts at the California Highway Patrol.”

Newsom admonished Trump for the event and said in the statement: 

The President is putting his ego over responsibility with this disregard for public safety. Firing live rounds over a busy highway isn’t just wrong — it’s dangerous. Using our military to intimidate people you disagree with isn’t strength — it’s reckless, it’s disrespectful, and it’s beneath the office he holds. Law and order? This is chaos and confusion.

The New York Times reported that a spokesperson for Vance criticized Newsom, stating the California governor “wants people to think this exercise is dangerous.” 

The spokesperson continued:

The Marine Corps says it’s an established and safe practice. Newsom wants people to think this is an absurd show of force. The Marine Corps says it’s part of routine training at Camp Pendleton. If Gavin Newsom wants to oppose the training exercises that ensure our Armed Forces are the deadliest and most lethal fighting force in the world, then he can go right ahead.

Snopes reached out to the Marines and the White House for further comment on what went wrong with the ordnance that exploded prematurely and to ask whether they planned to use the same artillery prior to the highways being shut down by the state. We also followed up with the press office of the vice president, who previously told Snopes that Newsom was spreading “fake news” regarding plans for the demonstration. We will update this article if we receive a response.