Elaine Herzberg, 49, was crossing a four-lane road with her bicycle when she was run down in a suburb of Phoenix, Arizona, at 10pm on Sunday.
Local police today said that while the Volvo was travelling at around 40mph in autonomous mode there was a back-up driver at the wheel, and early indications suggest the collision may have been unavoidable.
Police chief Sylvia Moir said: “It’s very clear it would have been difficult to avoid this collision in any kind of mode based on how she came from the shadows right into the roadway.
“The driver said it was like a flash, the person walked out in front of them. His first alert to the collision was the sound of the collision.”
The ride-hailing app has halted all trials of its self-driving fleet in Phoenix, Pittsburgh, San Francisco and Toronto in the wake of the fatal crash which has fuelled concerns over the safety of autonomous vehicles.
A spokesman said said: “Our hearts go out to the victim’s family. We are fully cooperating with local authorities in their investigation of this incident.”
Gatwick Airport is planning to test self-driving shuttle buses this summer.
Deniel Klapthor, one of Ms Herzberg’s friends, said: “It’s weird. One minute they’re here and the next they’re gone.
“Her and her husband split up recently and she was trying to get her life back and she was succeeding with it. The two last saw each other a couple weeks ago.
“She had come by here and she had her hair done real pretty and she had a smile on,” Ms Klapthor said.
Democratic Senator Edward Markey, a member of the transportation committee, said: “This tragic accident underscores why we need to be exceptionally cautious when testing and deploying autonomous vehicle technologies on public roads.”
Officers will pass CCTV footage from the crash to county attorneys for review and any potential charges.
