The alarm about a fire in an attic in Säffle came in to SOS Alarm at 7.30 pm on Saturday night.
At around 8 pm, smoke divers from the rescue service entered the smoke-filled apartment to search and see that there were no people left.
The fire had then spread in the apartment, but the fire could be extinguished relatively quickly and no one should have been injured.
Police on the spot made a report of a serious arson, and a man in his 60s is now under arrest on suspicion of the fire.