It was just before 9 o'clock on Monday that the rescue service and police responded to the first alarm.
By then, the stairwell had burned down and a report of a suspected arson was made.
A few hours later, at 13 o'clock, a new alarm came at the same address and then it burned inside an apartment.
Several people were evacuated and no one was injured.
- A woman in her 40s has now been arrested on suspicion of aggravated arson, says prosecutor Åsa Valter.
More calls together houses
The criminal suspicion against the woman is about yesterday's second call.
But even in June, the rescue service pulled out of a basement fire in the same house.
If that case and yesterday's first alarm have connections, the prosecutor does not comment during the ongoing investigation.
- The investigation continues and the crime scene is cordoned off, says Valter.
Before 12 o'clock on Friday, the prosecutor must decide whether the woman should be requested to be detained or released.