Uber said it is suspending self-driving car tests in all North American cities after a fatal accident.
A 49-year-old woman was hit by a car and killed as she crossed the street in Tempe, Arizona.
While self-driving cars have been involved in multiple accidents, it is thought to be the first time an autonomous car has been involved in a fatal collision.
Uber said that its “hearts go out to the victim’s family”.
“We’re fully cooperating with @TempePolice and local authorities as they investigate this incident”, the company said in a statement on Twitter.
Police said the accident happened Sunday night while the car was in autonomous mode. A human monitor was also behind the wheel.
Police said the woman, Elaine Herzberg, had not been using a pedestrian crossing. Herzberg, who police say may have been homeless, was taken to a local hospital where she died.
The US National Highway Traffic Safety Administration and the National Transportation Safety Board said they were sending teams to Tempe.