Four people were charged with the incident that took place at Hagaskolan in August, three of them are now sentenced.
Two of the people are convicted of aggravated assault and the third for attempted murder.
All of those involved must have had a relationship with each other through drug use and some have previously been convicted of drug offenses.
The district court considers that the man was attacked after being tricked into the scene by the suspects.
Two of the convicts are sentenced to over two years in prison, the third is sentenced to seven years in prison.
In addition, they are also convicted of other crimes such as theft and assault.