Uber has suspended all its self-driving car tests in the US after a fatal accident in Arizona.

A pedestrian was reportedly crossing the street in the city of Tempe when she was hit by the car.

The incident comes just a year after one of Uber’s self-driving cars was involved in another accident where no-one was hurt but one of Uber’s self-driving Volvo cars was flipped onto its side.

Uber’s CEO Dara Khosrowshahi tweeted that the death was “incredibly sad news” and that “we’re thinking of the victim’s family.”

It’s not yet clear what happened but Khosrowshahi said that Uber would fully cooperate with law enforcement to understand what happened.

We’ve reached out to Uber for an official statement on what might have happened but the Uber Comms Twitter account has already tweeted on the incident.

“Our hearts go out to the victim’s family. We’re fully cooperating with @TempePolice and local authorities as they investigate this incident.” it said.