On Monday, the police were alerted to Bellmansgatan in Eskilstuna by several people who had heard loud bangs in the area.
When the police arrived at the scene, a man in his 25s was found on the ground.
He was taken to hospital by ambulance, but his life could not be saved.
Since then, the police have carried out several investigative efforts that have now resulted in a 17-year-old being arrested and requested to be detained on suspicion of murder, the police state during a press conference on Friday.
The police state that the 17-year-old is already known to them.
The article is updated.