The westbound side of the 60 Freeway saw a significant backup Monday morning, after a fatal multiple-vehicle crash closed all lanes for a period of time during the morning commute.

The crash occurred around 2 a.m. in the Chino area of the 60 freeway, between Mountain Avenue and the Euclid exit, near the Ontario border.

The CHP’s Traffic Incident Information page noted three vehicles involved in the crash, but did not go into detail about the number of injuries or the exact number of fatalities. At least one person was declared dead at the scene of the crash.

Caltrans District 8 announced on Twitter that all lanes were open again around 7 a.m. Monday.

The cause of the accident is not yet known.

Traffic was backed up for miles, as authorities investigated the incident and diverted drivers to other routes.