There was a pallet storage yard adjacent to the expressway. Apparently homeless people had commandeered pallets to help build their structures. There may have also been RVs parked under the expressway.

News reports are saying almost nothing about the homeless encampment as the source of the fire. They say the cause is "still under investigation."

Long detailed video of the fire and firefighter's efforts:

https://youtu.be/4J-fD4mff8k?si=3ozPihDU9FBzEbto

Articles:

This is the only article that specifically blames the homeless encampment. Awaiting confirmation:

https://www.smobserved.com/story/2023/11/13/news/fire-at-homeless-encampment-under-santa-monica-freeway-closes-the-main-east-west-highway-in-los-angeles-county-for-3-months/7919.html

Fire at Homeless Encampment Under Santa Monica Freeway, Closes the Main East West Highway in Los Angeles County for 3 Months

"I-10 will be FULLY CLOSED until further notice between the East LA Connector and Alameda St due to a fire that damaged the freeway". CalTrans

A fire Saturday morning under the 10 freeway has closed the interstate for 3 weeks, while the California Depart of Transportation repairs damage to a bridge. The fire started at a homeless encampment and quickly spread to a storage facility with pallets and vehicles such as trucks. The fire was too intense for firemen to put out quickly. It burned for about 8 hours starting at 4 am Saturday morning. 150 firefighters, 12 trucks and a helicopter were involved in the fight.

According to David Ortiz, public information officer for the Los Angeles Fire department, a number of RV’s housing homeless people were parked under the bridge.

Governor Gavin Newsom has declared a state of emergency for Los Angeles County. Mayor Karen Bass has asked traffic officials to consider how to mitigate traffic.

"Both directions of the 10 Freeway near Alameda in Downtown Los Angeles are shutdown following a massive pallet fire. @LAFD on scene. CALTRANS is determining if the structural integrity of the freeway has been compromised."

CalTrans

10 Freeway is closed between Santa Fe and Alameda until further notice. Map

On Saturday 11.11.23, @Caltrans tweeted: "I-10 will be FULLY CLOSED until further notice between the East LA Connector and Alameda St due to a fire that damaged the freeway. Avoids the area, expect major delays & seek alternate routes to events in #DTLA or use @metrolosangeles public transportation.” https://x.com/CaltransDist7/status/1723429432118083665?s=20

~~~~~ more at ~~~~~

https://www.smobserved.com/story/2023/11/13/news/fire-at-homeless-encampment-under-santa-monica-freeway-closes-the-main-east-west-highway-in-los-angeles-county-for-3-months/7919.html