Two young people were arrested last week in San Francisco's Outer Richmond neighborhood after allegedly being caught in a Waymo with a loaded assault rifle, authorities said.

Waymo employees became aware of a firearm in one of the company's driverless cars on Sept. 3 and pulled the car over, a Waymo spokesperson told SFGATE. The company alerted emergency services and cooperated with the San Francisco Police Department.

Police were called to the 800 block of 40th Avenue just before 4 a.m. and carried out a "high-risk vehicle stop," Allison Maxie, a spokesperson for SFPD, told SFGATE. When officers searched the car, they found an "AR-styled assault rifle also known as a ghost gun," and in a search also found "suspected marijuana and mace spray," she said.

The two passengers, male and female, were arrested and booked into the Juvenile Justice Center, Maxie said. The young people are facing charges related to illegally possessing a firearm.

Police are not releasing the identities of the suspects because of their age. This is still an open investigation and anyone with information is urged to call SFPD at 415-575-4444.

In the past, Waymo employees have alerted local police departments to suspected illegal activity in the company's vehicles. In July, Waymo employees alerted the San Mateo Police Department about two 15-year-old boys who were allegedly drinking alcohol and shooting water beads while riding in the vehicle, SFGATE previously reported.

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This article originally published at 2 young people arrested after Waymo alerted San Francisco police about loaded AR-style rifle.