The suspect also said that “people get what they ask for” and that “he wanted to end his own suffering with this act”.
“The motive will be clarified during the preliminary investigation through interviews,” Tuominen said.
Police were alerted to the stabbing outside a shopping centre in central Tampere at 4:23 pm (1323 GMT) on Thursday.
The victims received first aid at the scene and were now receiving hospital care for “severe injuries”, according to police — though none of the victims had life-threatening injuries.
The suspect put up no resistance as he was arrested at the scene carrying a knife, police said.
Police were proceeding with an investigation into four counts of alleged attempted murder.
Tuominen added that the 23-year-old had a criminal record, including stabbing a person in 2023 and three counts of aggravated robbery while carrying a knife in 2020.
Finnish media on Friday also reported that police believed the man may have planned the act for a long period of time.
Police have requested the suspect be remanded in custody and a court hearing is scheduled for Monday.
According to Tuominen, they had several eyewitnesses to the attack, and the incident was over in about a minute.