Uber has announced to put a stop on its self-driving cars from the roads after an accident which left one of the vehicles on its side. Pictures posted online showed the car on its right side on an Arizona street, next to another vehicle in a bad shape.

The car - a Volvo SUV - was in self-driving mode at the time of the crash with no casualty and injury, on Friday, according to Uber's statement.

A spokeswoman for the police in Tempe, Arizona said the accident occurred when another vehicle "failed to encounter" to the Uber car at a left turn.

"There was a person behind the wheel. It is uncertain at this time if the person was driving the vehicle at the time of the collision," spokeswoman Josie Montenegro said.

It is noted that Uber's self-driving cars always have a human in the driving seat to be able to take control when needed. The company retracted its self-driving vehicles off the road in Arizona at first, followed by test sites in Pennsylvania and California, where it operated the vehicles.

This is yet negative news for Uber after a number of executives have reportedly quit in recent weeks, including the president, Jeff Jones. Uber's relationship with its drivers has become increasingly intensified, as the company admitted on Tuesday and vowed to improve its service.

In particular, drivers for the company will now be able to defend themselves against rider complaints and refunds with better rules applied

Uber also pointed out that it will continue its investigation into allegations of sexual harassment and "toxic" working culture. The news follows the recent departure of the company's president Jeff Jones, who said the "beliefs and approach" at Uber were not on par with his own views. Part of Mr Jones's job at the company had been to improve the relationship between the company and its drivers.