SAN MATEO, San Mateo County, Calif., Oct. 21, 2026 — Three vehicles collided on Tuesday morning, October 20, on northbound US-101 near the 3rd Avenue offramp in San Mateo, according to the California Highway Patrol. At least one person was hurt and taken for treatment.
The crash was reported shortly after 10:25 a.m. on the northbound freeway just south of the 3rd Avenue exit. Early reports described a white Mercedes SUV involved with a pickup truck and another vehicle, though accounts of the vehicles involved varied as more information came in. CHP later confirmed the collision involved a Chevrolet Camaro, a pickup truck, and a Mercedes SUV, with debris scattered across the roadway.
The impact left the Camaro with major front-end damage and the Mercedes SUV with major damage to its rear. Responders requested an ambulance for at least one occupant, and the log notes some occupants were out of their vehicles after the crash. The extent of injuries has not been released.
The crash blocked multiple lanes, including the express lane, prompting backups on the northbound side of the freeway. Tow trucks were called to clear the vehicles, and CHP closed out its incident response by late morning. No further details on the cause have been released, and the California Highway Patrol continues to review the circumstances of the collision.
We hope those who were hurt recover fully and quickly.
More Crash News from San Mateo County
This multi-vehicle crash happened on US-101 in San Mateo, CA. For other recent crashes near San Mateo, CA, visit our San Mateo County accident news page.
Frequently Asked Questions
Why do chain-reaction crashes like this happen?
Multi-vehicle pileups usually start when one vehicle slows or stops suddenly, and the cars behind it cannot react in time, especially in heavy highway traffic where following distances are already tight.
How can drivers avoid getting caught in a pile-up?
Keeping a safe following distance, watching brake lights several cars ahead, and avoiding distractions give drivers more time to react if traffic suddenly slows.
What should I do if I'm stopped near a crash on the highway?
Stay inside your vehicle if it's safe to do so, turn on hazard lights, and move to the shoulder if possible. Getting out near active lanes increases the risk of being struck by passing traffic.
Does fog or low visibility play a role in these crashes?
Reduced visibility from fog, glare, or heavy rain can make it harder for drivers to see slowing traffic ahead, which is a common factor in multi-vehicle collisions on highways.
What to Do After a Multi-Vehicle Crash in San Mateo, CA
If you're involved in a multi-vehicle collision, try to move to a safe area away from traffic if your vehicle is drivable, and check yourself and passengers for injuries before exiting. Call 911 to report the crash and request medical help even if injuries seem minor, since some injuries don't show symptoms right away. Exchange information with other drivers involved, and if possible, take photos of vehicle positions and damage before anything is moved. Getting a prompt medical evaluation afterward is a good idea, even if you feel fine at the scene, since adrenaline can mask pain or injury symptoms for hours.
