As a first reaction almost everyone has the urge of retribution of some sort, and I think it is natural as it's an emotional response. That's the way we are hardwired to respond to such shocks. Don't forget that we are not as civilised as we like to believe, we are still animals to a large percentage. Just because we can think logically and empathise it does not necessarily mean that we are benevolent spirits full of kindness - simply because otherwise incidents like the one on the article would never happen.
However once someone cools down they can obviously observe that the individual who committed this atrocity is ill beyond doubt. The way to treat ill people is to try and make them well, not punish them or act revenge on them. That is why there is a difference to whether you do something with intent or not. That is also why a judges job is so difficult and we - as a society - have let the job of judging to a few select individuals (well, all this sounds nice hypothetically, I doubt of its real application considering the judges I've seen/known).
So yes, the act is unthinkable and brutal. The individual needs help. The question is, can we rehabilitate him? Do we have the means yet to do something like that? If we can't rehabilitate him (as I suspect) what do we do?