Tesla says it doesn't yet know what caused the crash involving its Model X car in California on Friday, an accident that killed the driver.

Tesla's Model X struck a highway barrier on March 23 near Mountain View.

The company said that due to the extensive damage caused by the collision, the company has not yet been able to retrieve the vehicle's logs, and that it had been working with the authorities to recover the logs from the computer inside the vehicle.

The company added that the crash was so severe since the crash attenuator, a highway safety barrier which is designed to reduce the impact into a concrete lane divider, had either been removed or crushed in a prior accident without being replaced.

"We were deeply saddened to learn that the driver of a Model X vehicle involved in an accident last Friday passed away. Safety is at the core of everything we do and every decision we make, so the loss of a life in an accident involving a Tesla vehicle is difficult for all of us. Earlier this week, Tesla proactively reached out to the authorities to offer our assistance in investigating," the company added.

Tesla didn't disclose whether the driver had engaged Tesla's partially autonomous driving system, known as Autopilot, when the crash occurred.

The crash adds to Chief Executive Officer Musk's challenges including concerns that the electric-car maker won't reach its production targets for the all-important Model 3 sedan. The accident also potentially raises fresh questions about self-driving features after a deadly Uber accident that happened days earlier sent ripples across the broader autonomous-vehicle industry.

Tesla said its battery packs are designed so that when a fire occurs, it spreads slowly so people have more time to exit the car. "That appears to be what happened here as we understand there were no occupants still in the Model X by the time the fire could have presented a risk," Tesla said.

The U.S.authorities are also investigating the Uber accident in Arizona, in which the car's systems failed to slow the vehicle as a 49-year-old woman crossed the street pushing a bicycle. The pedestrian died from the collision.