Police have not tracked down the perpetrator, believed to be a boy aged 15 to 17.
The victim was found outside Björngårdsvillan in Slottskogen at 8 pm.
Both he and a witness were able to provide police with a description of the attacker.
So this website can function correctly please whitelist The Local with your adblocker, antivirus software or browser add on.
Please visit the help centre for more information