By “major,” they mean I-5. That must’ve wreaked havoc.

A celebration marking the US marines’ 250th anniversary will shut down a major freeway artery through southern California on Saturday as the military plans to fire live 155mm artillery shells over the site.

The California highway patrol announced the closure at 6am Saturday, saying it would shut down an approximately 17-mile (27km) stretch of Interstate 5 for four hours near Camp Pendleton, a 125,000-acre (50,585-hectare) base in Oceanside in north-western San Diego county. The closure will remain in effect from 11am to 3pm.

The event in question will include a live-fire amphibious capabilities demonstration at Red Beach, according to a statement from the US marine corps. JD Vance, a former enlisted marine who served in Iraq, is scheduled to speak to at least 15,000 marines, sailors, veterans and families expected to attend. Defense secretary Pete Hegseth will also deliver remarks.

“The capabilities demonstration will feature integrated Navy and Marine Corps operations across air, land and sea,” the Marines’ statement said.

The US Marine Corps insisted that the event will comply with established safety protocols, and “no public highways or transportation routes will be closed”.

The CHP said in a statement that the military event will involve “live ammunition being discharged by the federal government over the freeway” and made the call to temporarily close a portion of the freeway due to the safety risk and distractions to drivers.