The school, located in rural Värmland in western Sweden, has been reported by the Schools Inspectorate (Skolinspektionen) and police have launched an investigation into alleged assault, unlawful threats and coercing a minor.
Following reports of abuse, wideaspread bullying of younger students as well as threats and violence at Lundsberg, the agency carried out an unannounced inspection at the school, which educates the well-heeled up to high school level.
"In the reports we have uncovered evidence of violence of a nature which the Schools Inspectorate does not investigate, so we notified the police," said Carina Abreu, Schools Inspectorate inspector.
"It's severe violence," Abreu confirmed.
She says it's unusual that the inspection reports incident to the police, but said what has taken place at the school is a matter for public prosecution.
The unannounced inspection took place on October 20th. The principal, dormitory representatives and students were among those interviewed.
The school is said to apply a practice of so-called "peer education" whereby older students are tasked with educating younger - but incidents of violence have also been noted.
"There is an informal system that the school calls 'peer education' that also has these features," Abreu said.
The Inspectorate's own report on security breaches and student life at Lundsberg should be ready early next week.
"Then we will explain more in detail," said Abreu.
The school's principle, Staffan Hörnberg, has criticized the methods used during the inspection.
The Local reported last week that a pupil had filed a complaint that he had been subject to excessive bullying.
His report described being beaten after failing to bow when leaving a room; of younger students' rooms being checked with a cotton swab for cleanliness; and of being forced to do push-ups while older students kept watch, holding baseball bats.
On one occasion, some of the older students acquired electric fly swatters following an excursion to Ikea which they subsequently used to burn the boy's nipples with as punishment for some other alleged infraction.