Tributes to the teenager stabbed to death at an Aberdeen school have continued to pour in overnight as a wall of flowers appeared at the gates.
The victim of the attack at the Cults Academy, Bailey Gwynne, 16, was rushed to hospital but died later of his wounds.
Bailey Gwynne was described as a "very gentle, caring pupil, with lots of friends"
A 16-year-old has been detained by police to "help officers with their inquiries".
Anna Muirhead said: "Pupils and staff are in a state of total shock. The boy involved was a very gentle, caring pupil, with a lot of friends.
"I think it's fair to say the whole school community is totally devastated. At the moment of course our thoughts are all with the boy's close family and his friends and what they must be going through at this tragic time."
A candlelit vigil is scheduled for 8pm today.
Chief Inspector Graeme Mackie, of Aberdeen Police, said in a statement: "This is a shocking and extraordinary incident for Aberdeen and firstly our thoughts are with the family and friends of the boy who has sadly lost his life today.
"A full and thorough enquiry is underway and there will be a police presence in the area for the foreseeable future.
"We are working closely with the education authorities and wider community as I am sure this incident will be felt not only in Aberdeen but much further afield."
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Cults Academy Stabbing
The school will be closed for Thursday and Friday and specially trained officers have been interviewing pupils.