Very distrurbing. Six people left their home to pray and never came back.
It also makes me wonder. People with psychological problems exist at all times and places. Guns do too. Under what conditions do people decide to grab a gun, enter a building with people they do not like (mosque, gay bar, school, you name it), and use it?
I read the article, Bissonnette might have been disturbed, unlikeable person, but there is nothing exceptional in his prior behaviour that could serve as an explanation. He seemed to have had a normal, boring life similar to millions of other people.
Consider this too: although we have had our fair share political terrorism/violence here in Greece,on top of my head I do not remember any incident like what Bissonnette did in that mosque.
Does this work like a fashion where the perpetrators immitate a story they read in the news?