An autonomous Uber test SUV driving in Tempe, Arizona was involved in a fatal collision last night, and the Uber vehicle was in autonomous mode at the time the accident occurred, according to Tempe Police (via Daisuke Wakabayashi).

The Uber SUV was driving northbound, and a woman crossed in its path outside of a crosswalk, at which point she was struck by the vehicle. She was later taken to hospital, as first reported by local Arizona ABC news affiliate ABC 15, where she died as a result of her injuries.

As is required for Uber’s autonomous test vehicles operating on public roads, the AV had a safety driver at the wheel. Safety drivers are in place in order to be able to take control of the autonomous test vehicle in case the self-driving system should fail or appear to be at risk of endangering others on the road. No other passengers were in the vehicle at the time of this accident.

Uber has paused all of its AV testing operations as a result of this accident, across all cities where it operates, including Pittsburgh, Toronto, San Francisco and Phoenix.

Uber provided the following statement regarding the incident to TechCrunch:

Our hearts go out to the victim’s family. We are fully cooperating with local authorities in their investigation of this incident.

This is the first time an autonomous vehicle operating in self-driving mode has resulted in a human death, and that has huge implications for the future of AVs and their use on roads. It’s possible the safety driver involved could be held legally responsible, as their role is to ensure safe operation of the vehicle, but in many ways the outcome of this incident will define the path forward for AV regulation.

Uber CEO Dara Khosrowshahi expressed sympathy for the victim’s family on Twitter, and reiterated that Uber is working with local authorities to determine what exactly occurred.