According to the police, the incident occurred in the room that is rented out to various organizations. It is yet to be confirmed who had rented the room, and what meeting was held there.
"Three people were taken to a hospital," the police said, Sputnik reported.
The message about the shooting came at 05.52 (03.52 GMT). According to media reports, there were about 70 people in the event room.
Local newspaper Dagens Nyheter reported citing eyewitnesses that an uninvited guest came to the party and, after a quarrel, started shooting from a handgun.