The fire alarm came in at 03, and when the rescue service arrived on the scene the fire was fully developed and spread on the roof.
All the approximately 25 residents in the apartment block were evacuated, but no person should have been injured.
For those who have not been able to find a roof over the heads of friends or acquaintances, the cinema Borgen has been opened as a gathering room.
The police announced on Sunday morning that after investigating the site, an investigation into serious general carelessness was opened.
This article will be updated.