A masked perpetrator entered an apartment in Saltskog in Södertälje on Thursday.
When a woman in her 50s, who lives at the address, discovered the burglar, she was attacked.
The masked perpetrator ran from the scene after assaulting the woman.
Police have searched the area with dogs and spoken to neighbors, but no one has yet been arrested for the assault.
The woman is taken to hospital by ambulance. The extent of the damage is unclear.
It is unclear whether anything was stolen from the apartment, but at the moment the incident is classified as aggravated assault and burglary, the police write on their website.
The text is updated