August 27, 2026

A major 10 Freeway accident in Rosemead, California, caused significant traffic disruption Thursday morning after a semi-truck crashed into the center divider and overturned onto the Metrolink railroad tracks.

The collision happened in the early morning hours near Del Mar Avenue, prompting a response from the California Highway Patrol and emergency crews.

Several westbound lanes were closed while authorities worked to secure the scene and remove the overturned truck.

What Happened on the 10 Freeway?

The crash was reported at approximately 3:00 a.m. Thursday on the westbound San Bernardino Freeway near Del Mar Avenue.

According to preliminary information, the tractor-trailer struck the center divider before overturning and coming to rest on the Metrolink tracks alongside the freeway.

Images from the scene showed the large truck lying on its side across the railroad tracks.

The exact circumstances that caused the truck to leave its lane and strike the divider remain under investigation.

Driver Escapes the Crash

The truck driver was reportedly able to get out of the overturned vehicle.

At the time of the initial reports, no injuries had been reported in connection with the crash.

Authorities have not reported any fatalities from the incident.

The condition of the driver and whether the person required medical evaluation were not immediately detailed.

Westbound 10 Freeway Lanes Closed

The crash resulted in the closure of several westbound lanes.

The carpool lane and two left lanes were among those affected, while crews worked to clear the overturned tractor-trailer and repair damage to the freeway infrastructure.

A SigAlert was issued because of the significant traffic impact.

Motorists travelling westbound through Rosemead were warned to expect delays and congestion during the morning commute.

Metrolink Service Also Affected

Because the truck landed on the railroad tracks, the crash also affected Metrolink service.

The tracks between El Monte and Cal State LA were temporarily impacted while crews dealt with the wreck.

Rail service was later able to resume through the area as the emergency response progressed.

The incident demonstrated the potential for a freeway collision to affect both road and rail transportation in the San Gabriel Valley.

Cause of the Crash

The cause of the accident has not yet been determined.

Authorities have not indicated whether speed, driver fatigue, mechanical failure, road conditions or another factor contributed to the collision.

Investigators will need to examine the truck, roadway, available video footage and other evidence before determining what led to the crash.

Investigation Underway

The California Highway Patrol is handling the traffic investigation.

Officers are expected to document the scene and examine the circumstances surrounding the collision.

The investigation may also include an examination of the tractor-trailer and the damage caused to the center divider and railroad infrastructure.

No criminal cause has been announced in connection with the crash.

Traffic Impact

The accident caused considerable delays on the westbound 10 Freeway as commuters encountered lane closures during the morning rush.

Drivers were advised to use caution when approaching the affected area and to allow additional travel time.

The reopening of lanes depends on the removal of the truck and completion of safety inspections.

What We Know So Far

• The accident occurred Thursday, August 27, 2026.
• It happened on the westbound 10 Freeway near Del Mar Avenue in Rosemead.
• A semi-truck struck the center divider and overturned.
• The truck landed on Metrolink railroad tracks.
• Several westbound lanes were closed.
• A SigAlert was issued.
• The driver was able to exit the vehicle.
• No injuries were initially reported.
• Metrolink service was temporarily affected.
• The cause of the crash remains under investigation.

Developing Story

The 10 Freeway accident in Rosemead remains a developing traffic story as authorities continue clearing the scene and investigating what caused the semi-truck to overturn.

Additional information may be released regarding the investigation, road repairs and the full restoration of normal traffic and rail service.

Drivers travelling through Rosemead should expect possible delays and exercise caution around the area while crews complete their work.