At Del Mar Beach on Camp Pendleton, a Marine Corps brass band played jazz standards while thousands of Marines and sailors wearing camouflage mingled under the bright midday sun.

The event, "From Sea to Shore, an Amphibious Assault Demonstration," began at noon and runs the rest of the afternoon.

The demonstration includes firing artillery from a base beach into the base's firing ranges, the Marines said.

/ KPBS

"Marines will fire 155 mm high-explosive rounds from M777 howitzers," the Marines said in a statement Thursday. "The M777 will fire into designated ranges with all safety precautions in place."

Outside the base, Interstate 5 sits quiet — devoid of traffic after an early-morning decision to close the freeway for four hours during the event.

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