A Tesla driver is blaming Full Self-Driving software for having caused an eight-car pileup in the Yerba Buena Tunnel in California last month, according to a police report obtained by CNN Business.

According to the December 7th report obtained by CNN Business, California Highway Patrol (CHP) reviewed tunnel footage and found that a Tesla made an unsafe lane change before abruptly slowing down from 55 mph to 20 mph — causing vehicles behind it to crash into one another.

In the report, the driver of the Tesla blamed the automaker’s Full Self-Driving software that allegedly malfunctioned and caused a sudden slowdown. The Thanksgiving incident left nine people with minor injuries, including one child that was hospitalized.

California Highway Patrol said in the Dec. 7 report that it could not confirm if “full self-driving” was active at the time of the crash. A highway patrol spokesperson told CNN Business on Wednesday that it would not determine if “full self-driving” was active, and Tesla would have that information.

Earlier this year, an NHTSA report for crashes involving vehicles with ADAS showed Tesla topped the list. Tesla has said that the responsibility falls on the driver for the safe operation of the vehicle running on Autopilot or Full Self-Driving, but critics say the company is overstating the capability of its features.