Police said officers found "several injured people" outside the venue in the small industrial town of Molnlycke that hosted a party on Saturday. One remained in serious condition with gunshot injuries Sunday.
How many weapons were fired was unclear, and 13 people were arrested on suspicion of attempted murder and aggravated assault, police said.
News agency TT reported that Swedish prosecutors suspect the shooting was connected to a clash between two biker gangs, one of them connected to the Hells Angels.
Swedish authorities say the country has seen a rise in organized crime activity several gang-related shootings have taken place in its three major cities: Stockholm, Goteborg and Malmo.
Sweden - BN.