Police were called to a Durham school after a pupil was found carrying a pocket knife.
Officers attended New Brancepeth Primary School on November 22 following reports of a pupil having a knife.
Louise Templeton, headteacher of New Brancepeth Primary School, said the matter is being taken "extremely seriously".
She added: “As soon as staff became aware of the incident, the item was confiscated and the police and the pupil’s parents were contacted.
“No pupils or staff were injured during the incident and we are now working closely with the child concerned and their family in conjunction with the local authority and police.
“Support is being offered to other pupils at the school and we will be taking steps to ensure our children are fully aware of the issues this matter has highlighted.
“Incidents of this kind are incredibly rare and we would like to reassure families and the local community that we have robust measures in place to ensure the safety of all pupils in our care.”
A Durham Constabulary spokeswoman said: "On November 22, we were made aware that a pupil had taken a pocket knife into New Brancepeth Primary School.
"Police officers spoke to the child and his parents.
"They clearly explained to the pupil the dangers and potential consequences of carrying a knife, and that it is a criminal offence to carry one."
It comes after officers were called to Greenland Community Primary School in South Moor, Stanley earlier this year following reports of a pupil having a knife.
Officers in Peterlee also went to a school, which has not been identified, and seized a knife from a 15-year-old girl in March.
Last year, 12 offences were recorded by Durham Constabulary of young people carrying knives in Durham schools.
Information released under a Freedom of Information request, showed one youth was given a conditional caution, five were give pre-cautions and two resulted in 'community resolutions'.
Two cases involved action taken by 'other agencies' and in one, further investigations were deemed not in the public interest, Durham Constabulary said.