A woman in her 20s was subjected to a rape during the night against Sunday in Karlstad, the police write on their website.
The incident occurred near the river in the Klara district, and the perpetrator is said to have been unknown to the victim.
The alarm came in to the police at 03.24 and no one had been arrested for the crime by Sunday afternoon.
The police have held interrogations and conducted a crime scene investigation in the area during the day.
