Shortly after midnight, the police were alerted that about 20 people were involved in a large brawl on the school grounds.
There was stabbing to the right and left, so four people are in the hospital with knife injuries, of which two are seriously injured, says Michael Lindh, duty officer at Police Region South.
When the police arrived at the scene, only a few people were left and only one of the stabbed.
The other three had taken themselves to the hospital on their own, says Michael Lindh.
The case is being investigated as attempted murder, but it is still unclear what prompted the brawl. The police are holding interviews and going door-to-door in the area.
Of the eight arrested persons, four are those who sought hospital care. Seven of the arrested are in their 20s-25 years old and the eighth is in their 15 years old.
The area around the school is cordoned off for a technical investigation.
