The police were alerted to Vällingby shortly after 11 pm, after conversations about loud bangs that sounded like gunfire.
An injured person was found at the scene and has been taken to hospital, the police write on their website.
According to the police's first information, these were two injured people, but that information was corrected during the night.
The police are searching with a dog patrol for one or more perpetrators who must have left the place on foot.
A preliminary investigation into attempted murder has been launched.