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.