One person has been taken to hospital with what is currently assessed as minor injuries. There is no information about anyone else being injured in the explosion, says police spokesperson Anna Westberg.
The explosion occurred outside an apartment door. A wall inside the stairwell has been damaged and several window panes have shattered, according to the police.
The rescue service estimates that there is no risk of collapse in the stairwell.
The alarm came in at 22.41. No one has been arrested yet.
We have an operation with several different competencies where our ultimate goal is to apprehend the person or persons behind the explosion, says Westberg.
The police are investigating the incident as reckless endangerment and gross violation of the law on flammable and explosive goods.
