While this isn't the first fatal incident involving a self-driving vehicle, it does appear to be the first resulting in the death of a pedestrian. "Our hearts go out to the victim's family," Uber tweeted today.

Our hearts go out to the victim's family. We're fully cooperating with @TempePolice and local authorities as they investigate this incident. — Uber Comms (@Uber_Comms) March 19, 2018

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. https://t.co/cwTCVJjEuz — dara khosrowshahi (@dkhos) March 19, 2018

A spokesperson for the National Transportation Safety Board told us that the agency is sending a team to Tempe to investigate the accident. The Tempe police department has confirmed the reports and has said, "Uber is assisting and this is still an active investigation."