It was bound to happen eventually, but for the first time someone has died while using Tesla's Autopilot feature:
This is the first known fatality in just over 130 million miles where Autopilot was activated. Among all vehicles in the US, there is a fatality every 94 million miles.
It's indeed a tragic incident, but hopefully this doesn't have a long term negative effect on the wide scale implementation of autonomous driving.
Of note is that the man who died, Joshua Brown, has a YouTube channel filled with videos of him showing off how Autopilot works in a Tesla. One video in particular features a close call where a truck driver nearly merges into Joshua's Tesla and the Autopilot swerves to save them both.