Police have arrested a suspected perpetrator. He was arrested when he tried to escape from the suspected crime scene in Hökarängen on Saturday.
The injured woman was found by police in a stairwell in the area. She had stab wounds from some form of shelter. Her injuries are considered serious.
– It is not a knife but something else sharp that has been used, says police spokesman Ola Österling.
The police have initiated a preliminary investigation into aggravated assault and suspect that the crime took place both inside an apartment and in the stairwell.
The alarm came at 11.05 on Saturday.