Two men in their 20s were seriously injured and are being treated in hospital. They are not critically injured.
The police cordoned off the area and checked people and vehicles. Several people were detained in connection with this.
Two people, aged 25 and 30, are now being held on suspicion of attempted murder.
The arrest was made during the operation, says police spokesperson Daniel Wikdahl.
In total, six people were detained during the night. The other four have been questioned and then released, and they are not suspected of any crime, says Wikdahl.
The police suspect that the shooting is linked to serious organized crime.
The shooting took place on Rissne Square, and in connection with the incident, a restaurant's facade was damaged.
An investigation has been launched into suspected attempted murder and serious weapons offenses. The alarm was raised at 22.16.
