Uber Technologies Inc.’s troubled self-driving car program has gone from bad to worse as one of its vehicles ran over and killed a pedestrian in Tempe, Arizona, on Sunday evening.

The victim, 49-year-old Elaine Herzberg, is said to have been crossing a road outside a pedestrian crossing when an Uber test vehicle, operating in autonomous mode, albeit with a so-called “safety driver” behind the wheel, stuck her at around 10 p.m., according to local reports.

Precisely how the accident occurred was not originally known, but Uber reacted quickly, saying it would suspend its self-driving vehicle program until such time that an investigation into the accident is undertaken. “Our hearts go out to the victim’s family,” the company said on Twitter. “We’re fully cooperating with @TempePolice and local authorities as they investigate this incident.”

A later report noted that police at this stage believe that the Uber vehicle may not be at fault. It’s believed that the victim may have walked out into the path of the self-driving vehicle, giving the technology no time to react. “The driver said it was like a flash, the person walked out in front of them,” a Tempe police officer is quoted as saying. “His first alert to the collision was the sound of the collision.”

The accident is notable because it’s the first time an autonomous vehicle has killed someone outside the vehicle itself. Tesla Inc. still holds the position as having the first self-driving death after a man was killed in Florida when his Model S slammed into the back of a tractor trailor in June 2016. Tesla was cleared of responsibility for the accident in January last year.

Regardless of where the fault lies, the pedestrian death has given credence to self-driving car skeptics, who once again called for restrictions on the technology.

“Arizona has been the wild west of robot car testing with virtually no regulations in place,” consumer advocacy group Consumer Watchdog said in a statement. “That’s why Uber and Waymo test there. When there’s no sheriff in town, people get killed.”

Jason Levine, executive director of the Center for Auto Safety, also weighed in. “As always we want the facts, but based on what is being reported this is exactly what we have been concerned about and what could happen if you test self-driving vehicles on city streets,” he told Bloomberg. “It will set consumer confidence in the technology back years if not decades. We need to slow down.”

The accident wasn’t Uber’s first in Arizona. A crash involving another vehicle resulted in an Uber test vehicle ending up on its side in March 2017. Uber also suspended testing after that crash, but restarted it a month later. How long Uber will suspend testing this time is not yet clear.

Image: ABC15