The 16-year-old was arrested at Attleborough High School in Norfolk
A teenager arrested at a Norfolk school after threats were made on an internet website has been detained under the Mental Health Act.
The 16-year-old was arrested at Attleborough High School in Attleborough, on Tuesday.
The arrest came after a person in Canada alerted police after seeing threats to the school on the internet.
Norfolk Police said the youth had now been detained under the Mental Health Act and investigations would continue.
At the school officers seized a knife, matches and a canister which is believed to contain a flammable liquid.
The boy was then held on suspicion of threats to commit criminal damage and possession of an offensive weapon.
A police spokesman said the informant had no links with the school but had called the force switchboard after becoming concerned.
The boy was arrested at the school.