The head of the top US road safety agency cautioned autonomous vehicle developers in a letter Wednesday about what he called an “unacceptable” pattern of driverless cars interfering with the work of law enforcement and other first responders.

“To state it bluntly: An AV that cannot safely interact with first responders is a danger to the general public,” Jonathan Morrison, the administrator of the National Highway Traffic Safety Administration (NHTSA), wrote in a letter that he described as a “call to action” for technology developers.

Morrison wrote that NHTSA has documented a “clear pattern” of interference over the last few months, including incidents in which the vehicles drove into active emergency scenes, blocked ambulances and firefighters, and didn’t respond in situations involving flashing lights, fire, and traffic cones.

He directed developers to “immediately focus their resources on fixing this issue,” and said that the NHTSA would schedule meetings with each company by the end of July to hear about solutions.

Waymo declined to comment. In a written statement, a Zoox spokesperson said the company “takes first responder interactions seriously, and we support NHTSA’s push to hold the industry accountable,” and called responses to emergencies “a critical part of our technology development.”

Officials with several city law enforcement and emergency departments told NHTSA representatives in a closed-door meeting earlier this year that Waymo robotaxis were impeding some emergency responses, WIRED reported in April. One fire chief called the vehicles’ behavior in those situations a “safety issue for our crews as well as the victims.”

A San Francisco official told the agency that the company’s tech was “backsliding,” and the city’s fire chief said, “Waymo is frequently now blocking our fire stations from access.” A representative from Austin’s police department also said that Waymos tend to freeze in difficult situations, and the vehicles often fail to respond to officers’ hand signals in emergencies.

“I believe the technology was deployed too quickly in too vast amounts, with hundreds of vehicles, when it wasn’t really ready,” the Austin police official said, according to audio of the meeting obtained by WIRED.

Austin first responders appeared in a separate City Council meeting this spring to discuss how a Waymo robotaxi blocked an ambulance for two minutes as it tried to respond to a downtown mass shooting that killed three people and injured at least 14.

In this week’s letter, Morrison said his agency would “continue to exercise our enforcement authority for developers that do not address significant safety concerns.” NHTSA has issued several recalls related to autonomous vehicle technology in the last several years, including two related to Waymo’s behavior on flooded roads and near construction zones, and another related to Zoox robotaxis stopping in front of oncoming traffic. (The companies reported that both issues were solved through software updates.) A school district in Austin also worked with Waymo to train its vehicles to stop for school buses, though the fix didn’t immediately work.

In a press release Wednesday, the NHTSA also touted the Trump administration’s work to ease regulations preventing more autonomous vehicles from operating on public roads. Last month, in a boon for purpose-built robotaxi developers, including Tesla and Zoox, the agency made it easier for companies to deploy vehicles that don’t meet motor vehicle safety standards because they don’t have steering wheels, driver-operated brakes, or rearview mirrors.

Updated on July 9, 2026, at 12:45 pm ET: This story has been updated with statements from Waymo and Zoox sent after publication.