The alarm was received by the police shortly before 01:00 on Sunday night.
A man is said to have been found unconscious and taken to hospital by ambulance, according to TT.
The police tell Aftonbladet, which was the first to report on the incident, that the man has injuries from sharp or blunt force trauma.
There have reportedly been several reports of a fight in the Lindö area, where the man was then found.
The incident is being investigated as attempted murder, according to Aftonbladet.
The text is updated.