One aspect of the terrible tragedy in Norway has not been mentioned in the media. Since it took 90 minutes for the police to arrive on Utoy Island (and the long response time ought to be a matter for investigation), what difference might it have made if one person, just one, had been armed and trained in the use of a weapon and had been able to stop the mass murderer in his tracks, preventing him from killing so many young people?

Certain individuals don't like to talk about what they call a "cowboy mentality," but think about it. If there had been an adult security guard present with the skill to properly use a a weapon and if the killer had been shot after he shot the first of the teenagers, the mourning now taking place in Norway would be far less, though the loss of even a single innocent life is tragic enough.

Norway has gun laws which forbid the possession of an automatic weapon, except for collectors. As is the case with so many gun laws in the U.S., laws do not deter a criminal intent on committing a crime. Criminals are by definition law breakers.

Think of the difference an armed person might have made in stopping the shooters at Columbine High School in Colorado, or Virginia Tech, or so many other places known now by their names and cities. If the shooter had known about the possibility of a security guard, or armed young people, might that have deterred him? That is impossible to say. But it is not impossible to say if there had been one who might have shot back, the scope of this horrific killing spree might have been sharply reduced. Here is a list of mass shootings in recent years. Read about them and ask yourself how many might have been prevented if one person -- just one -- might have been able to shoot back.

Cal Thomas is America's most widely syndicated newspaper columnist and a Fox News contributor.