– People in the area have made observations and alerted the police, says police spokesperson Ola Österling.
The injuries are probably caused by a knife and are considered to be life-threatening, the police state on their website. The teenager was picked up by ambulance helicopter.
The police have cordoned off a stairwell which is the probable crime scene and technicians are carrying out a crime scene investigation.
A preliminary investigation into suspected attempted murder has been launched. No suspect has been arrested.
The article is updated