A woman has died in the US after being hit by an autonomous Uber car.
It is believed to be the first death involving a pedestrian and a self-driving vehicle on public roads.
The crash happened overnight from Sunday into Monday in the Phoenix suburb of Tempe, Arizona.
The victim was taken to hospital but died from her injuries.
The car was in autonomous mode with an operator behind the wheel when the incident occurred, police said.
Uber has been testing self-driving vehicles in Tempe and Phoenix for several months.
The mini cab hailing app firm suspended its autonomous vehicle programme across the US and Canada.
Its chief executive Dara Khosrowshahi wrote on Twitter: "Some incredibly sad news out of Arizona.
"We're thinking of the victim's family as we work with local law enforcement to understand what happened."
The death will alarm those responsible for developing driverless technology in the UK.
Chancellor Philip Hammond revealed in November that he wants fully driverless cars on public roads by 2021.
A "cluster of excellence" is being created along the M40 corridor to develop autonomous vehicles using existing testing centres in Birmingham, Coventry, Oxford, Milton Keynes and London.
AA president Edmund King told the Press Association: "This fatality in Arizona perhaps reminds us that autonomous cars are not infallible.
"We must embrace new technology that ultimately can bring great safety benefits but not at a rate that puts lives at risk.
"In the UK it is right that we are thoroughly piloting this new technology before taking our hands off the wheel on the high street.
"We need to show that the technology is safe before consumers will trust it and embrace it."
Uber is not among the firms and groups trialling autonomous technology in the UK.