Two young passengers travelling in an autonomous vehicle were arrested in San Francisco after police allegedly discovered an illegal “ghost gun” inside the car.
The San Francisco Police Department said the incident occurred shortly before 4 am on September 3 in the city’s Richmond District.
Although police did not identify the autonomous vehicle’s operator, a Waymo spokesperson confirmed that one of the company’s driverless cars was involved.
According to the spokesperson, Waymo stopped the vehicle after its system detected a “violation of our terms of service involving a firearm.”
The company subsequently contacted emergency services and “cooperated fully” with San Francisco police.
Police said officers carried out a “high-risk vehicle stop” before detaining the two passengers, identified only as a boy and a girl who were both juveniles.
A search of the vehicle allegedly uncovered a loaded AR-style assault rifle, along with “suspected marijuana and mace spray,” according to the police statement.
The two passengers were taken into custody and transported to a juvenile hall.
Authorities said the investigation remains “open and active” as they continue to examine the circumstances surrounding the incident.
The latest case is not the first occasion on which Waymo has alerted authorities about incidents involving passengers in its vehicles.
In July, the company contacted the San Mateo Police Department after two teenagers were reportedly found drinking alcohol and firing toy guns inside the back of one of its cars.
Waymo began as Google’s self-driving car project in 2009 before becoming an independent company in 2016. Since then, it has significantly expanded its autonomous ride-hailing operations.
Its distinctive driverless vehicles have become a familiar sight in cities including San Francisco and Los Angeles, although their presence has also generated unusual incidents and complaints.
The company expanded its paid service this month to San Diego, Denver and Tampa, Florida.
Waymo also received approval last month from the California Public Utilities Commission to operate in additional areas, including San Diego, Sacramento and parts of Orange and Riverside counties.
The autonomous vehicles have occasionally been at the centre of unusual incidents.
In July, a shirtless man in East Hollywood was reportedly filmed standing on top of a Waymo vehicle while dismantling parts of it.
In another incident in 2025, a man in downtown Los Angeles was taken into custody after he allegedly attempted to enter a Waymo and drive it away.
The San Francisco incident adds another unusual episode to the growing list of encounters involving Waymo’s driverless vehicles as the company continues expanding its autonomous transportation network
