WASHINGTON CNN — A driver told authorities that their Tesla’s “full-self-driving” software braked unexpectedly and triggered an eight-car pileup in the San Francisco Bay Area last month that led to nine people being treated for minor injuries including one juvenile who was hospitalized, according to a California Highway Patrol traffic crash report. CNN Business obtained the report detailing the crash through a public records request Wednesday. California Highway Patrol reviewed videos that show the Tesla vehicle changing lanes and slowing to a stop. 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. The crash occurred around lunchtime on Thanksgiving, snarling traffic at Interstate 80 east of the Bay Bridge as two lanes of traffic were closed for about 90 minutes as many people traveled to holiday events. Four ambulances were called to the scene. The pileup took place just hours after Tesla CEO Elon Musk had announced that Tesla’s driver-assist software “full self-driving” was available to anyone in North America who requested it. Tesla had previously restricted access to drivers with high safety scores on its rating system. “Full self-driving” is designed to keep up with traffic, steer in the lane and abide by traffic signals. It requires an attentive human driver prepared to take full control of the car at any moment. It’s delighted some drivers but also alarmed others with its limitations. Drivers are warned by Tesla when they install “full self-driving” that it “may do the wrong thing at the worst time.” The report states that the Tesla Model S was traveling at about 55 mph and shifted into the far left-hand lane, but then braked abruptly, slowing the car to about 20 mph. That led to a chain reaction that ultimately involved eight vehicles to crash, all of which had been traveling at typical highway speeds. Tesla’s driver-assist technologies, Autopilot and “full self-driving” are already being investigated by the National Highway Traffic Safety Administration following reports of unexpected braking that occurs “without warning, at random, and often repeatedly in a single drive.” The agency has received hundreds of complaints from Tesla drivers. Some have described near crashes and concerns about their safety. This summer NHTSA upgraded the investigation to what it calls an engineering analysis, an indication that it’s seriously considering a recall. NHTSA told CNN Business a few days after the Thanksgiving Day crash that it was gathering additional information from Tesla and law enforcement about the crash.