After the horror, the inquest begins - and it reaches deep into society.
Psychologists will speculate about what drove two teenagers to mow down fellow pupils at a Denver school before killing themselves. There will be investigations into their backgrounds and habits, and into their clan of outcasts with a grudge against the world. But one reason stands out for why they were able to turn this grudge into carnage - the gun.
Without these weapons, so readily available and so revered in American culture, even the most disturbed adolescent would find their ability to vent their 'anger' on passers-by curtailed. Tighter laws will not deter psychotics or evil individuals intent upon random murder. But legislation and tougher control would make it more difficult to get the means to work out hatreds and fantasies.
This terrible phenomenon is not restricted to the United States. It has been played out from Hungerford and Dunblane in Britain to Port Arthur in Australia. But it has only been in America that such mass shootings have been carried out on campus by pupils.
The right to bear arms, even by people still in their teens, is defended by the gun lobby as part of the broad rights of citizens to live in freedom. Of course most Americans who have guns never fire them in anger. But when that freedom enables young people to give such horrific effect to their obsessions, it is time to recognise that some aspects of the liberties which Americans so rightly prize bring with them risks which are simply unacceptable for society at large.
This incident will also raise questions about the alienation of youth, the impact of macabre cults, the glamourising of violence, the appeal of the anti-hero, and the decline of parental and teacher control. But imagine the outcry about the infringement of personal liberty if a teacher in Denver had tried to stop the boys wearing their black coats, or warned about their behaviour.
Old-style discipline, involving deference to authority and punishment, is passe. Until the advent of Dr Spock, it was common for children to be chastised, and yet their level of violence was no higher than what we see in today's more enlightened climate. It is a sign of progress that physical punishment is less acceptable; but this does not mean behaviour has improved.
That sad conclusion makes it all the more essential that firearms regulations are tightened in the US. The Clinton administration needs to take a determined lead, followed by Congress and state governors. For nothing to happen would be a sign of a nation escaping reality, and a final insult to the dead.