Uber has temporarily halted self-driving testing after a pedestrian was struck and killed by one of the ridesharing company’s autonomous vehicles in Tempe, AZ late Sunday night.

According to a Tempe police spokesman, the woman was crossing the street outside of a marked crosswalk when she was struck. The Uber vehicle was in self-driving mode with a human safety driver at the wheel, which is standard practice.

Uber has addressed the incident and tweeted a response saying, “Our hearts go out to the victim’s family. We’re fully cooperating with @TempePolice and local authorities as they investigate the accident.”

This is the first reported fatality involving a self-driving car.