"In the hearing, he denied the murder accusations," chief prosecutor Eva Morén tells TT.
A second suspect, a 35-year-old man, is still in hospital after suffering life-threatening injuries during the attack, which took place around 1 p.m. The police he could not be interrogated yet due to his poor condition.
The two men, who live at the same asylum center in Arboga, are suspected of murdering two shoppers, a 55-year-old woman and her 28-year-old.
Morén has confirmed that the alleged perpetrators, of Eritrean origin, used a knife in their attack.
Police are increasing security in asylum centers in the region to prevent attacks against refugees, TT reports.
During a press conference on Monday, police said they could not speculate on a motive for the attack. Police also said they see no links so far between the victims and the alleged perpetrators and that nothing points at a political motive.
"It's a crazy case," said Per Ågren, head investigator for the crimes. "We do not know what is the reason for this."
Strömbäck said eyewitnesses and security camera's helped officers track down one of the alleged attackers, who had run away from the crime scene. He described the arrest as uneventful and that the suspect is not known to have committed any past crimes.
"It has been a terrible day. All our thoughts go to the families affected," store manager Mattias Johansson told journalists gathered outside the store.
The Ikea store and surrounding shopping center were cordoned off by police, who evacuated staff and customers from the building.
The store will remain closed on Tuesday.