Self-driving vehicles have increasingly become the targets of vandals in Arizona with the police there recording at least 21 incidents over the past two years. This includes people pointing guns, jumping in front of the vehicles, slashing tires and throwing rocks.

The Arizona Republic reports that the very presence of the self-driving vehicles in the area appears to be the main trigger for the rage towards autonomous vehicles. Google’s Waymo vehicles are currently being tested in Phoenix, and the company recently launched a self-driving taxi service.

A woman was hit and killed by an Uber autonomous vehicle in Tempe, Arizona, in March.