A video published by police yesterday raises some serious questions about Uber’s driverless-car technology.

The news: A video released by the Tempe, Arizona, police department shows what happened moments before one of Uber’s autonomous cars killed a pedestrian on Sunday. The driver was recorded by a camera inside the car, looking down (perhaps at her phone) for several seconds. Gut-wrenchingly, she looks up at the last moment to see someone walking into the car’s path.

What it means: Her distraction is, in fact, an indictment of the car’s technology. Experts have long warned that partial autonomy lulls people into a false sense of security, causing them to become dangerously disengaged. It can take many seconds for a person to regain situational awareness if something goes wrong.

Sensor questions: What remains unclear is why the sensors aboard Uber’s vehicle failed to spot the pedestrian, who was wheeling her bike across the road. Although the scene is dark, the lidar on the vehicle should have spotted the pedestrian easily. Investigations by the National Highway Traffic Safety Administration and the National Transportation Safety Board may uncover any problems with the car.

Why it matters: Companies rushing to commercialize vehicle automation are testing experimental systems on public roads. Moving too quickly could put lives at risk and set back a technology that could ultimately help reduce the number of people killed and injured on the roads each year.