The other stabbing victim, a 23-year-old woman, was still in critical condition as of Thursday afternoon.
“The deceased is Marie Skuland, 17 years old from Kristiansand. She was employed as a summer worker at Coop Obs Sørlandsenteret,” acting prosecutor Cecilie Pedersen Hille of the Agder police district said.
The two stabbings occurred in different locations within the Coop store on Wednesday evening.
A 15-year-old girl has been arrested for carrying out the attacks.
At a press conference on Thursday morning, police reported that the injured 23-year-old had been flown to Oslo University Hospital during the night after initial treatment at Sørlandet Hospital.
"Her condition is considered critical," Hille said.
The police are now investigating whether there is any relationship between the victims and the 15-year-old, but so far they have nothing to indicate any previous connections.
“This occurred in a large shopping mall with many employees and a lot of witnesses. We are asking witnesses to make themselves known and we need more information about what happened,” Hille said.
Suspect escaped from child welfare centre
According to police, the 15-year-old suspect had escaped from a child welfare institution earlier in the day. The suspect was known to the police prior to this incident.
“She has been questioned but the interrogation had to be cancelled because of her condition. She has been admitted to the child and adolescent psychiatric department in Arendal,” Hille said.
The girl's defence lawyer, Hege Klem, said that she has met with her client but that they did not discuss the stabbing attack.
“She was not able to be questioned. She is in deep despair,” Klem told NTB.
An expert has been appointed to assess the 15-year-old's mental condition. She faces charges of murder and attempted murder.
Chaotic scenes in shopping centre
According to witness reports, the 15-year-old suspect was seen moving through the shopping centre with a large knife in her hands.
“She was young, shouting and crying. It was hard to understand what she said. But it sounded like she was calling for help,” one of the witnesses, Sebastian Storaas, told Fædrelandsvennen.
Several of the stores in the shopping centre locked their doors to shield customers and employees while the drama was unfolding.
According to one witness, the girl picked up a knife from a sushi restaurant, but it is uncertain whether this is the same knife used in the stabbings.
Kristiansand Municipality has activated its crisis team to deal with the aftermath of the incident.
"This is deeply tragic and an incredibly sad event. Our thoughts and deepest compassion go to the family of the deceased and the injured,” municipal spokesman Jørgen Kristiansen said.
The Coop Obs supermarket in Sørlandssenteret was closed on Thursday but planned to open its doors again on Friday.