Two people dressed in dark colors and wearing masks dart into a busy street on a hill in San Francisco. One of them hauls a big orange traffic cone. They sprint toward a driverless car and quickly set the cone on the hood.

The vehicle’s side lights burst on and start flashing orange. And then, it sits there immobile.

“All right, looks good,” one of them says after making sure no one is inside. “Let’s get out of here.” They hop on e-bikes and pedal off…

An anonymous activist group called Safe Street Rebel is responsible for this so-called coning incident and dozens of others over the past few months. The group’s goal is to incapacitate the driverless cars roaming San Francisco’s streets as a protest against the city being used as a testing ground for this emerging technology.