Yes; there's a listing [0] of violence committed during the protests since they started earlier in the year.
I think that the police will continue killing people until they are disbanded or restructured. History tells us that police in Chicago and NYC, for example, can be and have been the primary source of corruption and organized crime. Edit: Chicago's police ran a torture ring for years [2]; NYPD has earned a dedicated page for all of their corruption scandals and the most egregious misconduct [3].
Facebook isn't doing enough to curb police using social media to organize. I don't think that we're asking for censorship, so much as we're asking Facebook to stop implicitly supporting violence and hate. Compare and contrast the Rohingya genocide in Myanmar, where Facebook admitted [1], after half a decade of implicitly backing the genocide, that they had been too slow to respond to the problem.
Edit: Downvoters, what are you exactly upset about? In addition to actually answering the parent's question and providing a listing of instances, I'm directly addressing their concerns and preserving the context of the original article. Please use your words.
[0] https://en.wikipedia.org/wiki/List_of_police_violence_incide...
[1] https://en.wikipedia.org/wiki/Rohingya_genocide#Facebook's_r...
[2] https://en.wikipedia.org/wiki/Jon_Burge
[3] https://en.wikipedia.org/wiki/New_York_City_Police_Departmen...