It was the night before Wednesday that the police were alerted to a home in central Tranås.
A man in his 20s had been seriously injured and taken by ambulance to hospital.
- He has some type of stab or wound injury, and there is blood in the apartment, so he has been subjected to some sharp violence, said police spokesman Thomas Agnevik.
The injured man was operated on but was available to speak later in the afternoon and could be questioned.
A woman in her 40s was arrested - on probable cause on suspicion of attempted murder.
Chamber prosecutor Klas Hellgren does not want to say what the motive was and what excuse was used.
- We still have interrogations left to carry out, so we have to keep it, he says.
The man and the woman knew each other, but what relationship they had to each other is also still unknown.
The detained woman is written at an address in Västra Götaland.