It was on Thursday morning that a 15-year-old boy stabbed a man in his 40s at Källebergsskolan in Eslöv.
The man working at the school was seriously injured but his condition is said to be stable.
The 15-year-old who is a student at the school has now been arrested on probable cause on suspicion of attempted murder and was questioned on Thursday about the incident.
The police currently do not want to go further into what the boy has told and the motive behind the knife attack is still unknown.
The school is open between 10-13 on Friday and the municipality's crisis team is on site in the parish home in Eslöv for those who need support and comfort.