The alarm came to the police at 23.00 on Friday night.
A person had then been shot in a residential area in central Bålsta.
When the police arrived, they found the person who later died of his injuries.
Another person has been arrested on suspicion of murder.
- It is cordoned off at the site.
We are now carrying out various investigative measures, says Daniel Ågren, RLC officer at the police.
Pictures from the site show how the police have blocked off a villa.
The police are very secretive about the case and do not want to disclose either the gender or age of those involved.
The text is updated