The protests are not advocating violence, looting, etc.. How is anyone going to prevent lawless types from taking advantage of a chaotic situation? And what caused this situation? A long string of black people being murdered by cops on camera. Two by chokeholds, and one reaching for his ID in his own car probably being the most prominent. The recent one simply equated to the last straw, and rightfully so.
What's done is done (anyone committing of a crime needs to be brought to justice however, don't mistake my words for dismissing that), and we need to work on a society where such tensions are not created in the first place. Being angry that someone has a voice right now is not productive. On that note, were you just as angry when a group of armed white militants took control of government property a few years ago? Probably not because they were treated like guests.