I didn't comment on the Norway massacre. One tends to find oneself repeating previous comments on similar incidents almost ad nauseum; But in my profile I do mention that I spent many years as a tactical firearms team officer and I was an instructor and tactical adviser, so here I go again:
A good shot with a humble .22 sporting rifle (found in thousands of country homes up and down the UK) and pockets full of easily carried ammunition, could kill and maim dozens and dozens, including the responding police, be they armed response vehicle crew or the unarmed 99%, just as Ryan did in Hungerford and he had an AK47 military rifle. Isn't a .22 tiny? Relative to full bore ammunition, yes, but its a bit like asking which bullet will kill you best. Range of a .22? If he could see you, he could hit you, its as simple as that. Once contained he'd continue to be extremely dangerous to the police who would do well to keep him contained and either starve him or let the negotiators bore him to suicide or surrender.
There are no police teams sat waiting to be deployed to such incidents in a Chinook helicopter or any other helicopter, anywhere in the world, as far as I know. If we want to improve the impression that we take public and officer safety seriously, we could provide quicker access to long arms for the non tactical firearms trained police, but its no cure and would require a big chunk of money (not that this is reason not to). Thats the way we live.