The presence of Waymo self-driving cars in Arizona has certainly kicked up a hornet’s nest, it seems. People are bullying, harassing and even outright attacking the cars and drivers to such a degree that police have been called almost two dozen times over everything from tires being slashed to drivers feeling threatened.

The Arizona Republic has reported on details related to a number of these incidents, which have included instances of guns being pulled. One man so bothered by the presence of Waymo cars in his neighborhood even reportedly stood directly in front of one of the vehicles and wouldn’t move until police showed up.

In other instances, people have thrown rocks at the cars, chased them and even run them off the road. One thing these attackers don’t necessarily seem to be aware of is how the Waymo vehicles use a combination of radar and cameras to navigate their way around the city, which means they also capture footage that can identify harassers. Waymo, which is owned by Google parent company Alphabet Inc., has been testing its self-driving technology in the area since 2016 and also launched its Waymo One commercial taxi service in Arizona in recent days.

Certainly, 21 instances of harassing and threatening behavior would not in and of itself seem to suggest widespread, organized opposition to the presence of Waymo. The company gave a statement to Business Insider in response to a piece on the number of incidents which suggests the company sees them the same way: “Safety is at the core of everything we do, which means that keeping our drivers, our riders, and the public safe is our top priority,” a Waymo spokesperson told BI in an emailed.

“Over the past two years, we’ve found Arizonans to be welcoming and excited by the potential of this technology to make our roads safer. We believe a key element of local engagement has been our ongoing work with the communities in which we drive, including Arizona law enforcement and first responders.”

While there haven’t been that many incidents, relatively speaking, some of them do nevertheless sound pretty scary. According to the Arizona Republic, police charged one attacker with aggravated assault and disorderly conduct and also confiscated his revolver. One cop wrote in his report about the incident that the man — whose wife said he’d been diagnosed with dementia — said his wife usually keeps the gun locked up in fear that he might shoot somebody, and that the man also said “he despises and hates those (Waymo) cars and said how Uber had killed someone.”

That last comment is a reference to one of Uber’s self-driving cars killing a pedestrian in Arizona.