During the night to Sunday, a 50-year-old man was seriously injured with a sharp object.
I do not want to say more about the injured as the condition is uncertain at present, says the police's press spokesperson.
A 25-year-old man was arrested after a police operation involving, among other things, a dog patrol and a helicopter. The man is now detained as a suspect for attempted murder.
At 23.22, the police were alerted to a local in Flen. The incident is seen as isolated and is believed to have occurred indoors.