By Mike Baker BBC education correspondent

Luke Warmsley was stabbed in school

The fatal stabbing of Lincolnshire school pupil, Luke Walmsley, this week inevitably raised concerns over school security.

But, while no-one would want to minimise the horror of this tragic event, does it warrant a rush to action?

There are a number of reasons for caution.

First, incidents like this are mercifully rare. Of course, almost the first response of journalists, myself included, is to remind everyone of previous fatalities in schools.

Yet a closer look at these incidents reveals that fatal attacks by one pupil on another are exceptional, particularly if they occur inside school buildings.

Most fatalities have involved intruders, usually with no connection to the school.

For example, it was an intruder who killed a teacher and 16 children at Dunblane Primary School in 1996.

As the weekly American newspaper 'Education Week' put it: 'are schools safer when teachers pack heat?'

The fatal stabbing of London head teacher, Philip Lawrence, in 1995 and of a pupil at Hall Garth school, Middlesbrough in 1994 also involved intruders.

The second reason for caution is that much has been done to improve school security since these attacks happened.

Most schools now have better fences, more secure entrances, security cameras and intruder alarms.

There have also been changes in the law making it a criminal offence to carry knives or other offensive weapons on school premises and giving the police powers to search for knives inside schools.

The guidelines on disciplining pupils caught with offensive weapons have also been strengthened.

It is now easier to expel a pupil for a first offence and appeals panels cannot reinstate pupils who have been found in possession of weapons.

Metal detectors

So is there really any need to do more? And if so, what could be done which would make schools safer?

Not surprisingly, some commentators have looked to the United States of America where some schools have installed metal detectors to screen pupils and visitors.

In Chicago, they are now spending a million dollars a week on security which includes metal-detectors, x-ray machines and security staff.

The Chicago public high schools now have a minimum of two uniformed police officers and two full-time security officers on duty during school hours.

Guns, not knives, are the problem in the US

This heightened security has been in place since September following an audit of school safety.

At the time, the Chicago public schools' boss, Arne Duncan, said "that's the price we're paying for our society's appalling fascination with, and easy access to, guns."

Yet even in Chicago, where the general murder rate is high, killings inside school are very rare.

Moreover critics of extreme security in schools point out that metal-detectors would not have prevented outrages like the Columbine High School killings in 1999 where pupils made no effort to conceal their weapons.

For the USA as a whole, statistics do not show any increase in acts of school violence.

For 2001-2 there were five school-associated deaths, down from 22 the previous year and well down from the high of 56 a decade ago.

Statistics on violent deaths in schools in England are not collected by government. As a Department for Education spokeswoman put it: "We don't collect them because they are so rare."

They would almost certainly be much lower than in the USA even after allowing for the differences in the size of the school population.

Fortresses

It is guns, rather than knives, which are the real problem in the USA.

Just one indication of the differences between the two countries is the bizarre (to British eyes, at least) fact that in Utah it is perfectly legal for an adult to carry a concealed gun providing they hold a permit for it.

As the weekly American newspaper Education Week put it in a recent article: "Are schools safer when teachers pack heat?"

So, in the light of all this, one has to wonder how appropriate it would be for schools here to adopt some of the American innovations, such as metal-detectors.

Of course, particularly after Dunblane, there can be no complacency. But unless future events show this week's tragedy to be part of a growing pattern, there seems little case for rushing to action.

It is perhaps worth recalling the comments of Lord Cullen after his inquiry into the Dunblane tragedy.

He said that while schools should be as safe as possible a balance had to be struck and "it would be unacceptable to carry measures to the point where schools were turned into fortresses".