This is sadly where we are now. I can't see how this isn't politically motivated. The wedge deliberately driven into our political system, setting people against one another with intolerance, suspicion and paranoia, was bound to lead to violence.
My only surprise is that nobody has attacked a Tory MP sooner. Murder is no solution to the problems our society faces; but when politics pushes hatred and intolerance, creates desperation and anger, with seeming no end in sight and nobody able to do anything about it, then you reap what you sow.