The explosion occurred at 04.48 on Wednesday morning in connection with a restaurant in Vallentuna center.
An area around Tuna square is cordoned off, as well as entrances to the town hall, the culture house and a garage.
It is unclear what was damaged in the explosion, but no one should be injured.
- We assess it as minor property damage, some window has broken, says Eva Nilsson, Stockholm police spokesperson.
A preliminary investigation has been launched into general dangerous destruction, no one has been arrested at the moment.
The police will knock on the door and go through any surveillance cameras in the area.
The article is updated.