In English law, it's the difference between murder and manslaughter, for murder, as well as the act, actus reus, you also need the intention to kill, or cause serious harm, mens rea. Sometimes rendered as the guilty act, and the guilty mind.
Well said. There is the usual outpouring from the authorities, about clamp down, more regulations and the like, but we all know it won't happen, and there will be another catastrophe. Mind you, if it can happen in Switzerland, it could happen anywhere.