The killing of Philando Castile will haunt us for a long time to come. It was another in a sequence of sickening and all-too-regular events, but perhaps most notable was how quickly it was disseminated. That’s because Castile's girlfriend livestreamed the immediate aftermath of his shooting to Facebook Live.Now Facebook CEO Mark Zuckerberg has made a statement. He expresses his grief and shock at the footage, and says his thoughts are with those affected.“While I hope we never have to see another video like Diamond's, it reminds us why coming together to build a more open and connected world is so important -- and how far we still have to go,” Zuckerberg writes.Social media has already played a major role in helping to effect change. We need only remember the Arab Spring, in which widespread Twitter use enabled protesters to quickly and efficiently organize and avoid government crackdowns. Facebook and Twitter have also aided the Black Lives Matter movement by allowing the horrifying footage of police killings to quickly spread. Awareness is the first step in solving an issue.Read Zuckerberg’s full statement below.