A woman has been struck and killed by a self-driving Uber vehicle, in what is thought to be the first ever death involving a driverless car and a pedestrian.
Elaine Herzberg, 49, was crossing the road when she was hit by the self-driving Volvo, which had an operator behind the wheel but was in autonomous mode.
The car was being driven in a suburb of Phoenix, Arizona, as part of tests Uber are conducting throughout North America.
Uber has now halted all of its driverless tests, which were also being carried out in Pittsburgh, San Francisco and Toronto.
Uber CEO Dara Khosrowshahi expressed condolences on his Twitter account and said the company is working with local law enforcement on the investigation.
Depending on who is found to be at fault, the accident could have far-reaching consequences for the development of self-driving vehicles, which have been billed as potentially safer than human drivers.
The federal government has voluntary guidelines for companies that want to test autonomous vehicles, leaving much of the regulation up to states.
The US Department of Transportation is considering other voluntary guidelines that it says will help foster innovation, however transportation secretary Elaine Chao has said companies need to address public fears of self-driving vehicles
A poll showed that 78% fear riding in autonomous cars.
List of driverless car controversies:
In 2016 a Tesla driver was killed in the first known fatal crash involving a self-driving car.
In 2017 Uber took its self-driving cars off the road following an accident that left a Volvo SUV on its side in Arizona.
In 2018 another Tesla was caught in controversy when police found a man asleep at the wheel of one of its self-driving cars.
Uber is one of several automakers and technology companies competing to use driverless technology and it is not the first to come under fire for a lack of safety.
In 2016, Tesla driver Joshua Brown was killed when his Model S electric sedan collided with a truck, making him the first known fatality in a self-driving car.
In early 2018, another Tesla was caught in controversy when police found one stopped in the centre of a five-lane road.
The driver, who was asleep at the wheel, was arrested on suspicion of drunk driving.
He told police his car was in “autopilot”, Tesla’s semi-autonomous driver assist system.