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DIAMOND BAR, Los Angeles County, Calif., Oct. 1, 2026 — A six-vehicle crash shut down multiple lanes of northbound State Route 57 at Pathfinder Road in Diamond Bar on Tuesday afternoon, September 29, after a report of a car traveling the wrong way toward the scene.
The California Highway Patrol said the collision was first reported shortly before 3:40 p.m. and involved six vehicles blocking the HOV lane and lanes one through three. Airbags deployed in some of the vehicles, and fire crews responded to roll the vehicles as a precaution, the agency reported.
While crews were working the scene, a caller reported a red vehicle traveling the wrong way in the fast lanes, heading toward the crash site, CHP said. It was not immediately clear whether that vehicle reached the collision area or whether it was involved in any additional impact.
A silver Toyota Corolla was also reported stopped and blocking a lane near the scene. By late afternoon, lanes remained blocked while crews cleared wreckage and investigated. No fatalities have been confirmed. The extent of injuries has not been released, and the cause of the initial six-vehicle crash remains under investigation.
Our thoughts are with those who were injured, and we wish them a full recovery.
When Wrong-Way Crashes Are Most Likely to Happen
Wrong-way crashes cluster at specific times rather than spreading evenly across the day. Many happen after dark, particularly late at night and into the early morning hours, when a driver mistakenly enters a freeway off-ramp or crosses a median. Weekend nights see a higher share, tied in part to impaired driving.
Afternoon and evening commute hours bring a different risk mix. Heavier traffic volume, lane changes, and sudden slowdowns raise the odds of multi-vehicle chain-reaction crashes, even without a wrong-way driver involved. When a wrong-way vehicle does enter a busy freeway during daylight hours, other drivers usually have only seconds to react.
According to the AAA Foundation for Traffic Safety, 4,164 fatal wrong-way crashes on divided highways resulted in 5,730 deaths from 2014 through 2023. The combination of closing speeds and head-on orientation is a major reason these crashes carry a higher death toll than other freeway collisions.
Frequently Asked Questions
Does alcohol play a role in wrong-way crashes?
Impairment is a factor in a large share of wrong-way crashes, especially those that happen at night. Investigators typically check for alcohol or drug use as a standard part of the review.
Are wrong-way crashes more common on certain roads?
They're more frequent on divided highways and freeways with off-ramps that can be mistaken for on-ramps, particularly where interchanges are complex or poorly lit.
What causes wrong-way crashes?
Common causes include driver impairment, confusion at interchanges, medical emergencies, and drivers entering a freeway from the wrong direction after a wrong turn.
Why are wrong-way crashes so frequently fatal?
Because vehicles are typically closing at combined highway speeds in a head-on orientation, the impact forces are far higher than in a same-direction rear-end or sideswipe crash.
What to Do After a Multi-Vehicle Crash in Diamond Bar, CA
If you're involved in a multi-vehicle crash, try to move to a safe spot away from traffic if your vehicle is drivable and it's safe to do so. Turn on hazard lights and call 911 to report injuries and get help routed to the scene.
Even if you feel fine, it's worth getting checked by a medical provider. Adrenaline can mask pain from whiplash, concussion, or internal injuries that show up hours or days later. Keep a copy of the CHP incident report once it's available, and photograph vehicle positions and damage if you're able to safely do so.
Report the crash to your insurance company promptly, and keep notes on what you remember while the details are fresh, including the time, lane positions, and any road conditions.
