It's a horrific attack. It's basically the same sort of thing as a crazed Islamist shouting Allahu Akbar and attacking policemen, as recently happened in Paris. 

However: a) a lot of people pretend the Islamist attacks never happen - they don't want to know about it, or b) they say the Islamist attacker is just mentally ill and it's got nothing to do with Islam/Islamism.

Yes, my comment was meant to be facetious.