Concentrated around areas with bars and other nightlife establishments, the violence was directed unprovoked at individuals or small groups, according to earlier reports.
Of 11 incidents registered last weekend, police suspect more than one person in 7 of those incidents, NRK reports.
Up to 19 people had been arrested by police by Monday evening in connection with the violence.
Four of the violent incidents are yet to result in arrests, NRK writes.
Additionally, three were arrested – one of them a 17-year-old – after another 17-year-old was assaulted and robbed in Oslo on Monday.
In a press statement released on Monday, Oslo Police District released further details of the 11 incidents, all of which were considered unprovoked.
“Further investigation will clarify more relating to the circumstances and possible motives in individual instances. The incidents are under investigation and in an early stage of this, and their status may change,” the press message stated.
Chief of Police Beate Gangås told NRK on Monday that police did not believe there to be a connection between the numerous incidents.
“We are using a lot of resources to prevent incidents like this from happening and when they do happen, police investigate fully,” Gangås said.
Gangås also confirmed on television news programme Dagsnytt 18 that the majority of arrested individuals are Norwegian citizens.
Politicians reacted strongly on Monday to the weekend’s events, with Minister of Justice Jøran Kallmyr advocating easier pathways to imprisoning young offenders between the ages of 16 and 18.
“It is completely unacceptable that so-called youth gangs are going around the city making trouble and beating up innocent people,” Kallmyr said to NRK.
Kallmyr’s own uncle was among the people who were attacked, newspaper VG reported.
The age range of suspects in the incidents is between 16 and 30 years, according to the summary released by Oslo Police.
Gangås told NRK that she agreed with Kallmyr that new approaches were need to arrest the trend.
“We are seeing that there is an increase in the use of violence in youth cultures. That is concerning. Many use violence as a language, assaults are filmed and spread on social media. This is not a trend we take lightly,” Gangås said.
The police chief added that Oslo is a safe city in general and that only a small fraction of young people – around 3 percent – commit crimes.
But these group often breaks the law repeatedly, she said.
“We are talking about around 160 people who commit several crimes,” she told NRK.