Multiple Cruise autonomous cars have been spotted blocking traffic lanes in San Francisco and sending real drivers into a rage.

Two of the self-driving Chevrolet Bolt robotaxis were seen parked up in the middle of the road near a busy intersection at Sacremento St and Leavenworth St with their hazard warning lights flashing and taking up too much space to allow other cars to get by.

Elsewhere in the city, near the corner of Geary Boulevard and Franklin Street another Cruise Bolt had stopped halfway into a bus lane, forcing a Muni bus driver to maneuver around the stricken car, SFGate reports. And yet another Cruise vehicle was seen stationary in the middle of road on Sacremento St with its light flashing and music blasting form the radio despite nobody being on board.

A spokesperson for Cruise told SFGate the stoppages were down to a technical issue, but didn’t specify exactly what had gone wrong. Cruise is headquartered in San Francisco and a recovery team was dispatched to deal with the cars within 20 minutes, the company says.

Related: Cruise Has Developed Its Own Chips For Self-Driving Vehicles

“Safety is the guiding principle of everything we do,” Cruise said in a statement. “That means if our cars encounter a situation where they aren’t able to safely proceed, they stop and turn on their hazard lights, and we either get them operating again or pick them up as quickly as possible. This could be because of a mechanical issue like a flat tire, a road condition, or a technical problem. We’re working to minimize how often this happens, and apologize to anyone impacted.”

This isn’t the first time Cruise’s cars have caused traffic chaos in San Francisco. More than a dozen cars blocked traffic in an incident last July, and in May another car obstructed a fire truck, delaying its arrival to an emergency scene that resulted in damage to property and human injuries. And in a separate incident in April a Cruise Bolt was pulled over by cops for driving at night without its lights on.