Between the horrific bombings in Bali and Finland, and the shootings in DC, not to mention all the places where this kind of thing never stops, the world is a pretty gloomy place at the moment, and Australia is obviously not immune. There’s no easy answer to any of this. As far as I can tell, the Helsinki bombing was the act of a lone psycho, the Bali bombing was presumably done by Islamic terrorists of some kind, and the DC shootings could be either, or both, or something else altogether. Effective gun control, a successful campaign against Al-Qaeda, a resolution of the Israel-Palestine dispute might have prevented some of these acts. But these are some of the toughest things I can think of to do, and even if they were all successful there would still be plenty of other sources of terror in the world.
Given that we have been living with this kind of thing, in one form or another, for a long time, and will have to do so for the foreseeable future, we should be careful about being panicked into doing anything stupid as an ’emergency measure’.