The man was found in his store in Rinkeby after the police were alerted around 22:00 about what was initially believed to be an explosion.
Later, it was established that a fire with intense smoke development had broken out in the premises.
He has been subjected to a crime by individuals who then set fire to his store, says police spokesperson Ola Österling.
The smoke from the store spread through a duct in a basement to a residential building.
The man is being treated in hospital, but his injuries are not considered serious, given the circumstances, according to Österling.
The incident is classified as assault and aggravated arson. The police cannot comment on possible motives at present.
It's too early in the investigation for me to go into any details about it, says police spokesperson Anders Bryngelsson on Saturday morning.
