It was at 9 o'clock in the morning that the boy, who was then 16 years old, came to his school.
He had four knives with him in his bag and witnesses have told that he was partially masked and played loud music when he entered one of the classrooms.
Inside, he stabbed a student of the same age and a teacher in his 50s.
The teacher was slightly injured, but the student was seriously injured.
After the attack, the boy himself called the police and he was arrested just a few minutes later.
No hate crime
The 17-year-old - he has turned one since January - says that his motive was that he felt bad.
He has had close contact with the 15-year-old who was convicted of a similar school attack in Eslöv.
He is now in a SiS home where he feels better.
- And then I felt that because he started to feel better and stuff, maybe that would help me too, the 17-year-old has said in interrogation.
Unlike the act in Eslöv, no information has emerged during the trial that the now 17-year-old boy had any hate crime motive.
Not mentally disturbed
The 17-year-old has undergone a forensic psychiatric examination which shows that he has not suffered from any mental disorder.
Prosecutor Pernilla Tallinger has demanded closed juvenile care, but says that the penalty for an adult is 18 years in prison.
The boy is sentenced to three years in closed youth care.
He is convicted of three counts of attempted murder and two counts of aggravated unlawful threats.
SEE MORE: The prosecutor demands three years of juvenile detention
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If the perpetrator had been an adult, Pernilla Tallinger would have demanded 18 years in prison.
Hear more in the video.
Photo: Erika Dahlin Jönsson / SVT and from the preliminary investigation