An elderly man has been arrested after entering a secondary school carrying an imitation firearm.

Two armed police response units were sent to Huxloe School in Irthlingborough, Northamptonshire, after the intruder had entered the school demanding to see the deputy headteacher.

Headteacher Christine Staley said that throughout the incident the intruder had appeared calm and there had been no apparent risk to any of the pupils.

The man, described by the headteacher as appearing "sad", had wanted to discuss unspecified "problems" with the deputy head.

Children were in lessons during the incident and would not have been aware of the intruder, said the headteacher.

The man, believed to be aged about 70, is not known to have any connections with the school. He is being questioned at Wellingborough police station.

Schools have become extremely sensitive to the threat of intruders, following the attacks at Dunblane primary school in Scotland and more recent attacks in the United States including the murders of pupils at Columbine High School.

Last month, the government announced an extra £22m to help schools secure their premises with closed-circuit surveillance cameras and improved fencing.

In the United States, fears over the threat of attacks has meant that a number of schools in major cities have installed metal detectors and regularly use security guards.