The issues that gave rise to these incidents are not new. Back in 2014 Radley Balko wrote a fascinating history on The Rise of the Warrior Cop.
Rania Khalek has an excellent summary on the history outlined in Balko's book and on Twitter => Rania Khalek on Policing
In 2003, the Ontario Human Rights Commission completed their systemic review of racial profiling by police in Ontario and concluded with recommendations for actions. You can read it here => Paying the price: The human cost of racial profiling
The point is that sadly this is not new. While I completely sympathize with the anger, the riots and burning are not effective means to effect lasting change. Change requires a committed and engaged citizenry that works day in and day out on these issues. Many community leaders have been doing just that and incidents such as these reinforce the need to continue these efforts toward better policing and criminal justice reform.
For those unfamiliar with the background surrounding this issue, these links are very good reading for review and historical context.