The United States and Norway have a lot of distinct differences. Racial and social demographics, work ethic, the role of government in people's lives and more. Because there is virtually zero strife of any kind in Norway, it makes the world news when a man takes a perfectly legal-to-own bow and arrows and starts killing other people with it.
Which only proves the point that every pro-gun advocate has made for decades: The heart of the killer caused this to happen, not the tool.
Think of it this way: If you believe that "guns are evil," then the rifle used to kill JFK, or Dr. Martin Luther King, Jr. is especially evil, because they were used to bring about the untimely demise of men who were making a distinct positive change in the world.
Now, let's say I obtained one of those rifles and took it back in time to Germany 1923, before Hitler could carry out his "Beer Hall Putsch" that started his rise within the NAZI party ranks.
As an aside, you don't want to kill "baby Adolf," because the Universe would just put someone else on the track to run the NAZI's when he was there. It's best to disrupt it when you know he's the one.
If you kill Hitler in 1923, you stand a chance that WWII never happens. So, you have just saved the lives of over 100 million people who would have died if Hitler had come to power. So is that rifle still evil, or is it somehow good now, because it saved millions of lives?
My answer is, NEITHER. It is a tool, with no ability to operate on its' own. It has no consciousness or ability to reason so intent can be formed. A tool can only perform the function its' designed to do. For that function to be applied for good or evil depends on the wielder of the tool.
If you insist on taking away the power of men to perform evil, as a consequence you also destroy their power to perform good as well. When that ability, that choice, is destroyed, you remove the je ne sais quoi that separates men from ants.
Back to the story. Because this place is so peaceful, even the police weren't armed. In response to this horrific event, the police get to arm themselves with guns. The citizens don't. But whose asses are on the line until the police get there? You guessed it. The police won't be there until minutes after they're called, if they're called and if they decide to respond at all. Put yourself in that position, you're being attacked, people are dying around you. You manage to call 911 and the dispatcher says, "No police for you!" What are you going to do other than bleed and die? Having the proper tools to defend yourself and end the threat sounds pretty good in that case, don't they?