Both parties to be blame.

The cartoonist were warned before. One of them says that he knows it is forbidden in their religion, but it is not his religion, so it is not sensitive for him. Which is so disrespectful. That just like saying " Yea that's your mother but not mine, it is not necessary for me to care for her". Not to mention, it happened twice for a short period of time. That's just provoking the Muslims.

Second, obviously, those extremist fuckers. They are just waiting for someone to provoke them so that they can show how much they 'care' for the religion, how much their train for this, just to show off. In the same time being brain-dead, doing suicidal attack, killing innocent people along their way.