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FONTANA, San Bernardino County, Calif., Sept. 21, 2026 — A chain-reaction crash involving multiple vehicles shut down lanes on eastbound Interstate 10 near Citrus Avenue early on Sunday morning, September 20, according to the California Highway Patrol. Injuries were reported, though the extent has not been released.
The California Highway Patrol said the crash began before 5:15 a.m. with a two-vehicle collision, with one sedan left on the right shoulder and another vehicle blocking the off-ramp. Within minutes, additional vehicles became involved as traffic backed up in the dark, and one vehicle reportedly went over a center wall while another went down an embankment, dispatch logs show.
A second collision occurred nearby a short time later, involving a Chrysler sedan and a Volkswagen Jetta, according to the CHP log. By around 5:25 a.m., a reporting party's vehicle was described as being involved with four other vehicles, and callers estimated that five to six vehicles were tangled in the wreckage across the middle and right lanes. Investigators have not confirmed a final count.
Emergency crews closed multiple lanes and, at one point, held all traffic in the area while fire personnel and tow operators responded, the CHP said. At least one person was reported to have been transported from the scene, and several tow rotations were requested to clear the vehicles. Lanes began reopening after 5:49 a.m., with the roadway fully cleared by about 6:25 a.m.
The cause of the initial collision and how it triggered the additional crashes remains under investigation. It's unclear whether reduced visibility or another factor played a role, and no citations or arrests have been announced.
We wish those injured a full recovery.
What Actually Cuts Down Chain-Reaction Freeway Pile-Ups
Multi-vehicle pile-ups like the one on I-10 usually start small: one car stalls or clips another, and what happens next depends heavily on how much space and time the drivers behind it have to react. When following distances shrink, especially in low light or fog, a single stopped car in a lane can trigger four, five, or six more collisions within seconds. Wider gaps between vehicles give drivers room to brake or steer around trouble instead of adding to it.
Road design plays a role, too. Better lighting at interchanges, rumble strips, and clearly marked shoulders all give drivers more warning before they're on top of a hazard. Some agencies have also found that variable speed-limit signs, which slow traffic gradually ahead of congestion or crash scenes, reduce the severity of secondary collisions by evening out speed differences between vehicles.
Driver behavior still matters most in the moment. A driver going the speed limit but tailgating has far less time to respond than one maintaining a following distance of several seconds, even at the same speed. According to the National Highway Traffic Safety Administration, 28,595 large-truck occupants were injured in multi-vehicle crashes involving large trucks in 2023, a reminder that when the first collision happens on a busy freeway, the vehicles arriving next determine how far the damage spreads.
Frequently Asked Questions
What should I do if I come up on a crash already blocking lanes on the freeway?
Slow down well before reaching the scene, turn on hazard lights, and merge early if a lane is blocked. Avoid stopping in a travel lane if at all possible; move to the shoulder only if it's safe and there's no risk of being struck from behind.
How does darkness or fog make chain-reaction crashes more likely?
Reduced visibility cuts down the distance drivers have to spot a hazard and react. Stopped or slow vehicles become harder to see until a driver is nearly on top of them, which is often how a single crash turns into several.
Why does following distance matter so much in preventing pile-ups?
More space between vehicles gives a driver more time to brake or steer clear when something unexpected happens ahead. Tight following distances remove that buffer, which is often what turns one crash into a chain of them.
Are secondary crashes common after the first one clears?
Yes. Traffic backups from an initial crash often create new hazards, especially in low light, and additional collisions in the queue are a well-known risk until the scene is fully cleared.
What to Do After a Multi-Vehicle Crash in Fontana, CA
If you're involved in or witness a multi-vehicle crash in Fontana, move to a safe location away from traffic if you're able, and call 911 to report injuries or blocked lanes. Even if you feel fine, it's worth getting checked by a medical provider afterward, since some injuries from a sudden stop or impact don't show symptoms right away.
Keep a copy of the CHP incident report once it's available, and note down anything you remember, such as lane positions, timing, and weather or lighting conditions, while it's fresh. If your vehicle needs towing, ask the responding officer for information on the rotation tow list rather than accepting help from unmarked tow operators at the scene.
