These are attacks against some generalised symbol with which the killer is profoundly angry, usually because of a personal insult that triggers feelings of deep disquiet. The tragic events invariably lead to the death of the violent individual unless the police get them before they kill themselves.

In 1987 Michael Ryan was surrounded by police in Hungerford, Berkshire, after killing his mother and anybody who was in his path. They were able to get to him only after he had shot himself.

In some cases, notably in America, these spree killers have put themselves so directly in the line of fire that they have been called “suicide-by-cop”.

In the minds of these killers is a mixture of despair, anger and a seeking of an act of revenge that they believe will wipe away the insult that they feel has been inflicted on them.

The trauma of the death of the students at Virginia Tech that will spread across the university and the whole country will be magnified by the feelings of so many people who feel that they have should have been able to prevent it.

Doubtless there will be a call to review the availability of firearms. The National Rifle Association of America’s response is predictable too. They will point out that events such as this are not carried out by a rifle-wielding member of a weekend militia. There is no doubt that access to rapid-action shotguns makes these events even more destructive but as we have seen with suicide bombers, who are closer to spree killers than is often realised, if a person really wants to take their own life and kill others in doing so it is exceptionally difficult to prevent it.

David Canter is Professor of Psychology at the University of Liverpool

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