'Pull into a secure location': Here's what Waymo tells autonomous car test drivers to do when they're threatened (GOOGL, GOOG)

What does an operator of a self-driving car do when they're threatened or attacked by an angry motorist or pedestrian?

If you work for self-driving car company Waymo, you go to the nearest mall.

According to a spokesperson for Waymo, drivers feeling threatened on the road are instructed to find a secure location like a mall parking lot and decide whether or not to call 911.

Waymo has been testing its robo-cars on Arizona public roads for roughly two years. The cars have a Waymo employee in the driver's seat, serving as a back-up driver who can take control of the vehicle when necessary (the self-driving car technology is still not perfect).

Not everyone is enamored with the self-driving cars however, and the Waymo back-up drivers often find themselves on the front lines of anti-robot road rage. According to recent reports, Arizona residents have thrown rocks, brandished guns at and slashed the tires of the self-driving cars.

Over the past two years, there have been at least 21 incidents where police were notified, according to the Arizona Republic.

Read more: P eople are attacking Waymo's self-driving cars in Arizona by slashing tires and, in some cases, pulling guns on the safety drivers

Waymo's training manual encourages drivers to "report suspicious behavior. When it's safe to do so, pull into a secure location (E.g., a mall parking lot) and contact dispatch, or call 911 if you're being threatened or feel that you're in danger."

Most drivers, however, find it easier and more effective to use the hands-free option of calling the company dispatch center, the spokesperson told us. A call to Waymo dispatch will alert the entire fleet when incidents occur.

The spokesperson would not say how many threats have been reported to Waymo's dispatch center.

Waymo says there has not been a need to update its safety procedures for drivers, even as accounts of its cars being driven off the road by road-raged residents have surfaced.

"It's a pretty close-knit group of folks. They've had really great lines of communication and those continue," the spokesperson said.