Uber has been working hard to carve out its own piece of the burgeoning self-driving vehicle market. Uber has been testing autonomous delivery trucks and fleets of hailable self-driving vehicles in several major U.S. cities, and even feels it’s ready to begin rolling out cars without human drivers as early as 2019. However, every major technological leap forward is going to have its missteps, and in the case of Uber’s self-driving fleet, that misstep took the life from an Arizona woman. Is this just an unfortunate accident, or a sign that autonomous vehicles aren’t as ready to hit the roads as Uber and other companies tell us they are?

The incident occured in the early morning hours of Monday, March 19th when an autonomous Uber SUV approached an intersection on Mill Avenue in Tempe, Arizona. The SUV reportedly did not slow at all as it approached the intersection, striking 49-year-old Elaine Herzberg as she was walking her bike through the crosswalk. Herzberg was rushed to a local hospital where she was pronounced dead.

Uber is cooperating with authorities and is conducting its own investigation alongside Tempe police. The vehicle is said to have had a human backup driver riding along, although it is unclear how or why the human backup was unable to stop the vehicle in time. In response to this tragic accident, Uber has suspended all operations of its self-driving fleets which currently operate in several major U.S. markets.

Arizona is home to one of Uber’s largest self-driving vehicle fleets since the flat landscape and relatively mild and stable weather provide a consistent testing ground. This unfortunate accident could change that, however. It’s currently unknown how Arizona or federal lawmakers will respond to what has now become the first fatal accident involving a self-driving car and a pedestrian. Is this a sign that we’re not quite ready for robot cars?