In February, Uber extended the test of its self-driving cars to Arizona, USA, and has been running hitch-free since then until this morning when one of the cars crashed, involving two other vehicles in an accident, that thankfully left no one seriously injured.

According to reports, one of the other two cars involved in the accident failed to yield to the SUV, hitting it and resulting in the vehicle flipping over and landing on its side. It was also reported that the autonomous vehicle had a driver in its driver’s seat who was there to take over driving if the anything went wrong, as is typical of all the self-run cars currently being tested.

The accident was first reported by twitter handle @FrescoNews.

As a follow up, Uber has grounded its entire self-driving fleet in Arizona, including the two other regions it was being tested in: Pittsburg and San Francisco, while the accident is being investigated.