NEW YORK (AP) — The top U.S. auto regulator opened an investigation Monday after a Tesla using an automated driving feature slammed into a Texas home at high speed and killed a 76-year-old woman standing inside.

The National Highway Traffic Safety Administration said it’s opening a special investigation into the Tesla Model 3 crash on Friday near Houston, a significant probe because the car was using technology that Elon Musk considers key to the company’s future.

The Tesla CEO is rolling out robotaxis using automated software in several U.S. cities this year and plans to invite Tesla owners to put their cars into the fleet using the same system across the country.

The driver told the Harris County Sheriff’s Office that he was using the technology, according to a police report on the crash, but it’s not clear what role, if any, it played in the incident.

Tesla did not respond to a request for comment but the head of the company’s artificial intelligence efforts suggested on social media later Monday that the self-driving feature was not to blame.

“In this case, the driver manually overrode self-driving by pressing the accelerator all the way to 100% of the accel pedal in this residential area,” wrote Ashok Elluswamy on X, the platform that is now part of Musk’s rocket company, SpaceX. “They reached a speed of 73 mph during the crash, and had the accelerator pressed even after the crash.”