The National Highway Traffic Safety Administration (NHTSA) has opened a preliminary investigation into approximately 2,000 of Alphabet's Waymo self-driving vehicles. The probe follows reports that the company's robotaxis may have failed to adhere to traffic safety laws concerning a stopped school bus. The investigation was prompted by a media report showing a Waymo vehicle maneuvering around a school bus that had its red lights flashing and stop arm extended while students were disembarking. NHTSA noted that given the millions of miles Waymo's fleet has driven, the likelihood of similar past incidents is high. This inquiry puts Waymo's autonomous driving system under increased regulatory scrutiny as officials review how the technology interacts with pedestrians and observes traffic laws. In a separate incident in February, Waymo had recalled 444 of its self-driving vehicles after two minor collisions in Arizona.