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SAN MARCOS, San Diego County, Calif., Oct. 24, 2026 — A two-vehicle crash shut down part of westbound State Route 78 near Twin Oaks Valley Road on Friday afternoon, October 23, according to the California Highway Patrol. The collision involved a white Ford Mustang and a gray Honda Civic, both of which came to rest on the roadway shoulder.
The crash was reported shortly before 2:15 p.m. Dispatch logs show the call was initially classified as a collision with unknown injuries before being updated to reflect that medical personnel were en route to the scene.
The collision remains under investigation. Our thoughts are with those who were injured, and we wish them a full recovery.
More on Crashes in San Marcos, CA
This crash happened at State Route 78 and Twin Oaks Valley Road in San Marcos, CA. We cover crashes across San Diego County as they're reported, and you can browse the latest in our San Diego County accident reports.
Frequently Asked Questions
What usually causes crashes like this one?
Collisions on highways often stem from a mix of factors, including following too closely, unsafe lane changes, distraction, or a driver misjudging another vehicle's speed. Investigators typically review all of these possibilities before determining a cause.
Does speed make a difference in how serious a crash is?
Yes. Higher speeds mean less time to react and more force at the moment of impact, which tends to increase the severity of injuries and vehicle damage.
Why is distracted driving considered such a serious risk?
Even a few seconds of taking your eyes off the road, to check a phone or adjust a dashboard screen, can mean missing a sudden stop or lane change by another driver, especially at highway speeds.
What to Do After a Car Accident in San Marcos, CA
If you're involved in a crash on a highway, try to move to a safe area such as the shoulder if your vehicle is drivable and it's safe to do so. Turn on hazard lights and check yourself and any passengers for injuries before stepping out of the vehicle. Call 911 even if injuries seem minor, since some symptoms, like those from whiplash or internal injuries, don't show up right away. Getting checked by a medical provider afterward creates a record that can matter later. Once everyone is safe, exchange information with the other driver and, if possible, take photos of the vehicles and the surrounding roadway. Filing a report with CHP or local police helps establish an official account of what happened.
