Police made several arrests following the incident, which took place at a restaurant in the city centre.
"A number of people have been detained and we're interviewing a number of different people who have information to provide," Anne Asp of the Östergötland County police told the TT news agency.
A dispute between two gangs precipitated the shooting. Two men were shot, while a third man was stabbed in the chest.
A 31-year-old man from Malmö was taken to Linköping university hospital with life-threatening injuries. The two other victims are said to be in serious, but stable condition.
Police remain tight lipped about exactly how many people were arrested following the shooting and what sort of connections they may have to the victims.
Nor are they willing to comment on reports that the shootout was a settling of scores between two rival criminal gangs.
"I can't go into that now. We're not finished with all of our interrogations yet," said Asp.
However, duty officer Ronny Dahlqvist of the Östergötland County police confirmed that police believe gangs were involved.
"This is gang-related and we know in which circles we should look," he told the Expressen newspaper.
According to eye witnesses, one of the shooting victims had a shirt with the emblem of the Outlaws motorcycle gang.
Meanwhile, another police source told Expressen that they believe the rival Black Cobra criminal gang may have carried out the attack.
The results of the police's forensic investigation are expected to be completed by Wednesday morning. Later in the morning, investigators are expected to meet with prosecutors about the case.
"We'll be working all night and we'll continue tomorrow. We're devoting all our resources to this, plus a little more," said Asp.