The driver at the heart of last month’s Thanksgiving pile-up in San Francisco has told authorities that Tesla’s self-driving software was to blame, according to ABC7.

Nine people suffered minor injuries when their vehicles were entangled in an eight-car collision on the towering Bay Bridge around lunchtime on 24 November, causing major traffic delays throughout the area.

Now, one of the drivers has reportedly told authorities that the crash was triggered by his Tesla electric car’s “full self-driving” mode, which had been launched to all North American customers just hours before the crash.

A report by the California Highway Patrol on 7 December says that the driver’s Tesla Model S was driving amidst fast-flowing traffic when it switched into the leftmost lane and then suddenly braked, causing a chain reaction, according to CNN.

A spokesperson added that the Highway Patrol has not yet confirmed whether full self-driving mode was active during the crash.

The company warns drivers that “full self-driving” is still in beta mode and requires “active driver supervision” at all times in case the software makes an error.

A message on the cars’ control console tells drivers, per ZDNET: “It may do the wrong thing at the wrong time, so you must always keep your hands on the wheel and pay extra attention to the road. Do not become complacent.”

On the morning of the crash, Tesla’s chief executive Elon Musk had announced that full self-driving would now be available to all customers in North America as long as they had bought the option to activate it.