NHTSA cites a pattern of robotaxis blundering into fires, blocking ambulances and ignoring flares, and gives developers until month’s end to explain how they will fix it. In a two-page letter addressed simply to “Driverless Automated Driving System Developers,” the National Highway Traffic Safety Administration’s administrator, Jonathan Morrison, told the industry that a recurring failure had become impossible to ignore — autonomous vehicles that do not know how to behave around police officers, firefighters and paramedics. The agency said it had documented multiple instances of driverless cars driving into active emergency scenes and blocking the paths of ambulances and firefighters, or failing to recognize and respond to basic safety conditions like flashing lights, flares, smoke, fire and traffic cones. In the letter, Mr. Morrison did not mince words about what that means for the technology’s credibility. “An AV that cannot safely interact with first responders is a danger to the general public,” he wrote. A pattern the agency says it can no longer treat as background noise The letter arrives after months of scattered but mounting incidents involving robotaxi fleets, most of them operated by Waymo, the Alphabet-owned company that has become the most visible face of driverless ride-hailing in American cities. Local media in Texas reported that a Waymo vehicle in Dallas partially blocked a route fire trucks were using to reach a burning apartment building in late May. Other videos have circulated showing Waymo vehicles blocking an ambulance and driving through an active police scene. Both NHTSA and the National Transportation Safety Board are now investigating separate incidents involving Waymo vehicles, including one in which the cars passed stopped school buses with their lights activated, in violation of Texas law, and another from January in which a self-driving Waymo struck a nine-year-old girl in a Santa Monica school