A Swedish football league match was called off during the first half after a Djurgarden supporter died from injuries sustained in an assault before the game in Helsingborg.
Police said the the 43-year-old man was found 'seriously injured' in central Helsingborg around 2:30 pm and was taken to a hospital, where he later died.
It's time we do something about this as we can't send our children to the arenas and not have them come home again.
Local media said the Djurgarden supporter had been hit in the head by an object after rival fans started fighting before the game.
His name was not released by police, but Swedish media said he was a father of four and Police said no arrests had been made in connection to the killing.
The season-opening game between Helsingborg and Djurgarden was called off in the 41st minute with the score 1-1 after angry Djurgarden fans tried to storm the pitch when word spread that the man had died.
The death overshadowed the opening round of the Swedish league season with politicians, players and clubs all calling for an end to fan violence.
Fights between hooligans are still fairly common in Sweden, but this was the first fatal fan violence since 2002, when a 26-year-old man was killed during clashes between supporters of AIK and IFK Goteborg in Stockholm.
"The Djurgarden family is in mourning,'' the Stockholm club said in a statement. "We can't describe in words how we're feeling right now.''
Helsingborg also issued a statement on its website saying 'we feel an enormous emptiness' over the incident and that 'Swedish football is united in the fight' against violence.
Larsson issues statement
Henrik Larsson, the former Celtic, Barcelona and Manchester United striker who played for Helsingborg in the Swedish league and now trains second-division club Falkenberg, told reporters that the violence has to stop.
"It's time we do something about this as we can't send our children to the arenas and not have them come home
again,'' Larsson was quoted as saying.
Former UEFA President Lennart Johansson, a Swede, said dealing with fan violence is a matter for both Swedish authorities and the European football body.
"We have to find clearer measures through a co-operation between clubs, police and authorities,'' Johansson told Swedish media.