The attack, which occurred at the school, has been labelled by police as aggravated assault. The Swedish Schools Inspectorate (Skolinspektionen) stated on Monday that the attackers had used an iron.
The student, who is new to the school, has been shifted to three different hospitals since Saturday, although his injuries have been described as minor.
In October, the Swedish Schools Inspectorate told the school that it will impose a 500,000 kronor ($75,000) fine if it didn’t act to stamp out the practice of bullying and violence among pupils.
The school, which is the alma mater of Prince Carl Philip and many other high society members, has had a bad track record with students assaulting others in hazing rituals.
In May last year, students at the school spoke out after being forced into oral sex and eating manure.
In 2011, a student had their nipples burned with an electric fly swatter.
Founded in 1896, Lundsberg was inspired by British boarding school tradition and currently has an enrollment of around 200 students, around 60 percent of which are boys.