Hjorne's luxury home in Marstrand on Sweden's west coast was almost completely destroyed in the attack Friday night, The Local reported.
Hjorne, who along with his daughters owns 72 percent of the Swedish media outlet Stampen AB, was at his home in Gothenburg at the time of the fire.
"I was awoken by neighbors who called and said that it was alight," Hjorne told Goteborgs-Posten, which is owned by Stampen AB. "Naturally we are both sad and shocked."
The upper floor of the Marstrand home was completely destroyed in the fire and the lower floor sustained serious water damage, the news report said.
Hjorne said it is still unclear what started the fire, but as soon as the wreckage cools, it will be inspected by police.
"We have no knowledge of any threats towards the family," police spokesperson Bjor Blixter told Swedish news agency TT.
"A preliminary investigation has been opened and the classification is suspected arson," said Robert Edh with the Vastergotaland police.