SAN MATEO, San Mateo County, Calif., Oct. 16, 2026 — Three vehicles collided on Thursday morning, October 15, on northbound US-101 near 3rd Avenue in San Mateo. The crash blocked four lanes of traffic and prompted a request for ambulance crews to respond.
The California Highway Patrol's traffic log describes a black Honda two-door, a gray Toyota SUV and a blue Toyota sedan involved in the collision, which was reported shortly before 11 a.m. Lanes 1 through 4 on northbound 101 just south of 3rd Avenue were blocked as crews worked the scene.
An ambulance was requested for at least one injury, though the number of people hurt and the extent of their injuries have not been released. San Mateo County emergency medical crews responded to assist.
The cause of the crash has not been determined. The CHP has not said which vehicle, if any, was found to be at fault, and the incident remains under review.
We hope everyone who was hurt makes a full and speedy recovery.
More on Crashes in San Mateo, CA
This multi-vehicle crash happened on US-101 in San Mateo, CA. We cover crashes across San Mateo County as they're reported, and you can browse the latest in our San Mateo County accident reports.
Frequently Asked Questions
Why are crashes involving three or more vehicles usually harder to sort out than two-car wrecks?
Investigators have to reconstruct the order of impacts, since each vehicle's damage can reflect more than one collision. Witness accounts, dashcam footage, and skid marks all help establish which impact happened first.
What typically triggers a chain-reaction crash like this one?
These pile-ups usually start when one vehicle slows or stops suddenly, whether for traffic, a hazard, or another collision, and following vehicles can't stop in time. Heavy highway traffic and short following distances make the chain reaction more likely.
Is there anything a driver can do in the moment to avoid getting pulled into one?
Leaving extra space ahead and watching traffic several cars ahead, not just the vehicle directly in front, gives drivers more time to react if brake lights appear suddenly up the line.
What to Do After a Multi-Vehicle Crash in San Mateo, CA
If you're involved in a multi-car wreck, try to move to a safe spot out of traffic if your vehicle is drivable and it's safe to do so. Call 911 and stay put until officers arrive to sort out what happened among the vehicles involved. Even if you feel fine, it's worth getting checked by a medical provider, since injuries from a collision don't always show symptoms right away. Take photos of all vehicles involved and get contact information from other drivers and any witnesses nearby. Keep a copy of the CHP incident report once it's available, since it can take time for details from a multi-vehicle scene to be fully documented.
