Police said that patrols rushed Saturday evening to the small industrial town of Molnlycke, southeast of Goteborg, where they found "several injured people" following a shooting outside an entertainment venue that was hosting a party.
Police said events leading to the shooting were unclear. It is being investigated as an attempted murder.
According to the Goteborgs-Posten newspaper, several of the wounded have links to the Hells Angels biker gang.
Swedish authorities say the country has seen a rise in organised crime activity in the past few years. Several criminal gang shootings have taken place in its three major cities: Stockholm, Goteborg and Malmo.