RolandX, You aren't seriously suggesting Bernie Sanders is "radical left"? All of his policy platform was informed by programs that existed/exist in the U.S. or policies common in many countries of the world (universal, single payer health care, tuition free post-secondary). I have seen nothing to suggest the shooter was part of any other group.  

As for the centre, lets not forget how often the so-called centre is the government and is not afraid to unleash police violence. The G20 in Toronto for a recent example. Canada's history is littered with the "centre" using extreme violence to quell movements they do not like (Winnipeg General Strike, Mitch Hepburn and the Oshawa Strike).