A government report says the driver of a Tesla that slammed into a firetruck near Los Angeles last year was using the car's Autopilot system when a vehicle in front of him suddenly changed lanes and he didn't have time to react.
The National Transportation Safety Board said Tuesday the driver never saw the parked firetruck and didn't brake.
Apparently the man's 2014 Tesla Model S didn't brake either.
The report raises further questions about the effectiveness of Tesla's system, which was in operation before several other crashes including two fatalities in Florida and one in Silicon Valley.
Tesla warns drivers that the system is not fully autonomous and drivers must be ready to intervene.
The NTSB report didn't state a cause of the crash.
The agency will issue a final report Wednesday.
The driver in the Jan. 22, 2018 firetruck crash on Interstate 405 was not hurt.
But the NTSB report says he did not have his hands on the steering wheel at the time of the crash.
The Tesla driver, from suburban Woodland Hills, told the NTSB that he was traveling to work in Los Angeles when the crash happened.
He told investigators he was looking forward with his hand rested on his knee while touching the bottom of the steering wheel.
The California investigation comes as the federal government has few regulations governing autonomous vehicles and driver-assist systems that can drive a car under certain circumstances.
The systems can significantly reduce crashes, but computer-driven vehicles also can make mistakes.