What happened

Around 4 a.m., a Tesla Model S crashed into a Contra Costa County fire truck that was parked diagonally with flashing lights on northbound I-680 to protect responders at an earlier accident. 

The truck was parked to shield a crew clearing another accident, fire officials said. 

The Tesla driver, Genesis Mendoza-Martinez, was pronounced dead at the scene, and the passenger was critically injured and hospitalised. Four firefighters suffered minor injuries. 

The fire truck was severely damaged and towed away after the collision. 

Why it happened

The National Highway Traffic Safety Administration (NHTSA) confirmed the Tesla was operating under an automated driving system, specifically Autopilot, when it crashed, and failed to adequately detect or respond to the parked emergency vehicle.

The crash is one among at least 15 reported Tesla Autopilot collisions with emergency vehicles while using the system, and is part of a broader investigation into Tesla Autopilot crashes involving stationary emergency vehicles. The Tesla Model S involved was also under a recall for potential flaws in its "Full Self-Driving" system.

Tesla has stated its Autopilot and Full Self-Driving are advanced driver-assist features that require driver attention, but issues in detection and response have raised accountability questions.