Arizona residents have attacked self-driving cars with rocks and slashed their tyres.

Police reports obtained by local media suggest that the Chrysler Pacifica cars run by Google sister company Waymo have become a target for some disgruntled locals, with 21 incidents recorded in the past two years.

One car had its tyres slashed while parked and Waymos have had rocks thrown at them on five occasions, the Arizona Republic reported.

One man aimed a gun at the backup driver of another Waymo car as it passed his driveway. He was arrested and charged with aggravated assault and disorderly conduct. His wife told police that he suffered from dementia.

A dark Jeep appears to have targeted the cars on six occasions, swerving abruptly towards them or braking sharply in front of them.

On another occasion a “heavily intoxicated” man deliberately blocked the path of one of the cars by standing in front of it.

“He stated he was sick and tired of the Waymo vehicles driving in his neighborhood, and apparently thought the best idea to resolve this was to stand in front of one of these vehicles,” an officer wrote in a police report.

Suspicious residents of Chandler, Arizona, have called police on parked Waymos three times in 2018, the reports show, including one occasion where a woman called about a car which had been stationary near an area where children were playing for 90 minutes.

When contacted by officers the driver said he had been conducting diagnostics on the vehicle and left the area.

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A Waymo spokesman told the Arizona Republic: "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."

It is not clear how the level of incidents involving Waymos compares to the prevalence of vehicle crime in the area more generally, but the cases suggest that there is public discomfort that self-driving car companies still have to overcome.

Waymo, originally Google’s self-driving car project and now part of its parent company Alphabet, has been testing its cars in the area, a suburb of Arizona state capital Phoenix, for 18 months.

It has been running an early rider programme which involved more than 400 Phoenix residents using the cars to travel within an area of the city, believed to be around 100 square miles.

Earlier this month it announced that it would begin opening up access to the vehicles to the public as a commercial taxi service, known as Waymo One.

The cars can be summoned with an app and users will pay for them in a similar way to established ride-hailing apps such as Uber and Lyft.

Currently the programme is only open to members of the early rider scheme, who will be moved from the testing group to the commercial group as the service expands.

The company has begun testing cars without backup drivers, but the Waymo One service will be launched with the drivers still in place.