DETROIT >> The U.S. government’s road safety agency is investigating Tesla’s “Full Self-Driving” system after getting reports of crashes in low-visibility conditions, including one that killed a pedestrian.

The National Highway Traffic Safety Administration said in documents that it opened the probe on Thursday after the company reported four crashes when Teslas encountered sun glare, fog and airborne dust.

In addition to the pedestrian’s death, another crash involved an injury, the agency said.

Investigators will look into the ability of “Full Self-Driving” to “detect and respond appropriately to reduced roadway visibility conditions, and if so, the contributing circumstances for these crashes.”

The investigation covers roughly 2.4 million Teslas from the 2016 through 2024 model years.

A message was left Friday seeking comment from Tesla, which has repeatedly said the system cannot drive itself and human drivers must be ready to intervene at all times.

Last week Tesla held an event at a Hollywood studio to unveil a fully autonomous robotaxi without a steering wheel or pedals. Musk, who has promised autonomous vehicles before, said the company plans to have autonomous Models Y and 3 running without human drivers next year. Robotaxis without steering wheels would be available in 2026 starting in California and Texas, he said.

The investigation’s impact on Tesla’s self-driving ambitions isn’t clear. NHTSA would have to approve any robotaxi without pedals or a steering wheel, and it’s unlikely that would happen while the investigation is in progress. But if the company tries to deploy autonomous vehicles in its existing models, that likely would fall to state regulations. There are no federal regulations specifically focused on autonomous vehicles, although they must meet broader safety rules.

NHTSA also said it would look into whether any other similar crashes involving “Full Self-Driving” have happened in low visibility conditions, and it will seek information from the company on whether any updates affected the system’s performance in those conditions.

“In particular, this review will assess the timing, purpose and capabilities of any such updates, as well as Tesla’s assessment of their safety impact,” the documents said.

Tesla reported the four crashes to NHTSA under an order from the agency covering all automakers. An agency database says the pedestrian was killed in Rimrock, Arizona, in November of 2023 after being hit by a 2021 Tesla Model Y. Rimrock is about 100 miles north of Phoenix.

The Arizona Department of Public Safety said in a statement that the crash happened just after 5 p.m. Nov. 27 on Interstate 17. Two vehicles collided on the freeway, blocking the left lane. A Toyota 4Runner stopped, and two people got out to help with traffic control. A red Tesla Model Y then hit the 4Runner and one of the people who exited from it. A 71-year-old woman from Mesa, Arizona, was pronounced dead at the scene.

The collision happened because the sun was in the Tesla driver’s eyes, so the Tesla driver was not charged, said Raul Garcia, public information officer for the department.