Dutch child dies in school attack
A 22-year-old man has been arrested as a suspect in the killing of Jesse Dingemans, police said.
The attacker was not related to the boy, the son of a local bank manager, and the motive for the attack was not clear, police said.
The attack took place in the town of Hoogerheide, 150km (90miles) south of Amsterdam, near the Belgian border.
"The killer fled but police have now arrested a suspect," said police spokesman Willem van Hooijdonk.
"It does not seem that many children witnessed the incident," he told Dutch broadcaster NOS.
"As far as we can reconstruct it did not happen in front of a full classroom."
The boy is believed to have been stabbed when he went to an empty classroom to retrieve something.
The school was evacuated after the incident, while a helicopter hovered overhead. No murder weapon has been found.
The BBC's correspondent in The Hague, Geraldine Coughlan, said the killing has shocked the Netherlands.
School killings are rare in the country, which has strict laws on possession of weapons.
The Dutch Education Minister has said schools must be a secure environment for children.
A Dutch teacher was shot dead by a student and another seriously injured in a stabbing two years ago.