The fire was reported at about 2:30 a.m. Sunday on the island of Dalaro in Stockholm's archipelago, the Swedish news agency TT reported.
When authorities arrived at the scene, they found two bodies inside the house. There were unconfirmed reports that the victims were children.
The suspect, whose name was not released, rented the house for the past 2 1/2 years, TT said.
"He's been here about every other weekend, when he had his children," the property owner told TT.
The property owner, who lives in a larger house on the same plot of land, said he was not home at the time of the fire.
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