After the run of terror attacks in France this looks really, really bad.
Honestly this doesn't seem like all that much more than background noise. We're going to have to expect to see low level political violence for the foreseeable future.
That doesn't make it okay, of course, but I hardly think this constitutes a new worrying trend. It's an old worrying trend.
"When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first." - Werner Heisenberg (maybe)