According to the police, it is a window on a door that has been smashed.
The police bomb technician is on the scene.
The street was closed to tram traffic.
- What happens is that we have a safety distance, says Anders Wennergren, the police officer on duty to SVT Nyheter Väst.
The explosion is said to have occurred in a stairwell.
No injuries have been reported.
Police have no suspects.
- We do not have the indications that it was something huge that exploded, says Anders Wennergren, the police officer on duty to SVT Nyheter Väst.
At 06:20, SVT Nyheter Väst spoke with Västtrafik's disturbance management.
And the message was that the traffic would soon start moving again.
- It will start rolling very soon, but it may take a while before the traffic rolls according to the normal timetable, says Carina Kjellgren, Västtrafik's disruption management.
The text is being updated...