Waymo pulled its robotaxi over and called police on riders found with a ghost gun

Two juveniles arrested after the car stopped mid-trip

Two young riders were arrested in San Francisco in the early hours of Sept. 3 after the robotaxi they were travelling in was halted by its operator and police were called, according to the Los Angeles Times. Police said the incident took place shortly before 4 a.m. in the city's Richmond District.

Officers carried out what the San Francisco Police Department described as a high-risk vehicle stop and detained two juvenile passengers, a boy and a girl, whom the department did not identify further. A search of the car reportedly turned up a loaded AR-style rifle, described by the Times as a "ghost gun," along with suspected marijuana and mace spray. Both riders were taken into custody and brought to juvenile hall, and police say the investigation remains open and active.

The police statement did not name the vehicle's operator, but a Waymo spokesperson confirmed to the Times that one of the company's cars was involved.

How Waymo describes what happened

According to the spokesperson, the company stopped the vehicle after detecting a breach of its terms of service that involved a firearm, then alerted emergency services and cooperated with San Francisco police.

What the account does not explain is how the violation was detected in the first place. Neither the company's statement nor the police account specifies whether it came from monitoring inside the cabin, a report from someone outside the vehicle, or some other channel — a gap that matters as these fleets grow.

A pattern, not a one-off

This was not the first time Waymo has flagged suspected misbehaviour to law enforcement. In July, according to authorities cited by the Times, the company contacted the San Mateo Police Department after two teenagers were found drinking alcohol and shooting toy guns in the back of one of its vehicles.

The September episode goes a step further, though: the car was stopped mid-trip and the riders were met by police, rather than the company simply passing a tip to investigators afterwards.

Rapid growth alongside strange headlines

Waymo traces its origins to Google's self-driving car project, started in 2009, and became a standalone company in 2016. Per the Times, it launched paid service in San Diego, Denver and Tampa this month, and last month won permission from the California Public Utilities Commission to operate in San Diego, Sacramento and communities in Orange and Riverside counties, among other areas.

The company's cars have also drawn attention for odder episodes: in July, a shirtless man in East Hollywood was recorded standing on top of a Waymo while taking it apart, and in 2025 a man in downtown Los Angeles was taken into custody after allegedly trying to get behind the wheel of one and drive it away.

Why it matters

The San Francisco case appears to be the most notable example yet of an autonomous vehicle being pulled over by its operator and effectively summoning police against the people riding in it, based on the operator's reading of its own service terms. That capability sits uneasily with how many riders think of a taxi journey: as private transport, not a monitored service that can end in a high-risk police stop.

It also raises practical questions that neither Waymo nor the police have answered publicly. What is observed inside these cars, how suspected violations are judged, who makes the call to involve emergency services, and what happens to riders who are stopped but ultimately not charged? As driverless fleets expand into more cities, riders, regulators and police departments will need clearer answers about when a robotaxi is simply a ride — and when it is also a witness.