A 35-year-old man has been assaulted in Bromma, Stockholm, and has been taken to hospital with life-threatening injuries.
It's about some kind of blunt instrument, says the police's press spokesperson Daniel Wikdahl.
A 40-year-old man has been arrested and is suspected of attempted murder.
The police do not want to comment further on the course of events or potential motives.
We have a hypothesis about what it might be about, but we can't go into that right now.
The incident is said to have occurred outdoors in a residential area and several people are reported to have witnessed the incident.
The police are now conducting a technical investigation of the scene and a door-to-door inquiry in the area.