According to Finish Police, the knifeman who killed two people in the southwestern city of Turku on Friday appeared to choose only women as targets.
Police are treating the attack as a terrorist incident.
The suspect, arrested after being shot by police, is an 18-year-old Moroccan man. Four other Moroccans have been held after the incident.
Both women stabbed to death were both Finnish while eight injured, among them a Briton, a Swede and an Italian aged between 15 to 67.
PM Juha Sipila told a press conference that Finland had experienced a terror attack for the first time.
Police said in a statement: “The act had been investigated as a murder, but during the night we received additional information which indicates that the criminal offenses are now terrorist killings.”
They said the identity of the 18-year-old Moroccan was known, but they have not released it.
At a later press briefing, they said the suspect had arrived in Finland in 2016 and had “been part of the asylum process”.
National Bureau of Investigation spokesperson, Crista Granroth, said: “It seems that the suspect chose women as his targets because the men who were wounded were injured when they tried to help, or prevent the attacks.”
Candles were lit at the scene of the stabbings in Turku
Four people were arrested and an international search warrant has been issued for a sixth suspect.
The 18-year-old Moroccan man is still being treated in hospital for a gunshot wound to the leg. Two other people are also still in the hospital.
The UK embassy in Finland said, “it had been in touch with the British national and offered consular support”.
The attack happened in the Puutori/Market Square area of Turku.
Police said the alarm was raised at 16:02 local time (13:02 GMT) on Friday.
Police said he was arrested at 16:05.
One eyewitness, Laura Laine, told Reuters: “First thing we heard was a young woman, screaming like crazy. I thought it’s just kids having fun… but then people started to move around and I saw a man with a knife in his hand, stabbing a woman.
“Then a person ran towards us shouting ‘he has a knife’ and everybody from the terrace ran inside. Next, a woman came into the cafe. She was crying hysterically, down on her knees, saying someone’s neck has been slashed open.”