A man of the same age has been arrested and is being detained on suspicion of murder.
The victim’s common-law wife was a witness to the shooting. She is reported to be suffering from shock.
“We know that she has seen some of what happened, but as yet we don’t know how much,” said Christer Angeria at Nacka police to news agency TT.
The couple’s five-year-old daughter was also in the house at the time and was asleep upstairs.
According to Angeria the case centres around a relationship drama. The suspect has previously been involved with the dead man’s common-law wife.
Police arrived at the scene shortly after 10pm. The man was arrested 40 minutes later north of Stockholm. He was at the time sitting in his car and had the murder weapon with him.
The man was interviewed by police during the night and a murder investigation was then opened.
According to the newspaper Aftonbladet, the man has admitted to having murdered the victim.
None of the parties involved in the case are previously known to the police.