A teenage Moroccan asylum seeker has admitted to killing two people and wounding eight in a knife attack in the Finnish city of Turku, his lawyer said.

In a closed-door court hearing, 18-year-old Abderrahman Mechkah confessed to carrying out Friday's attack but did not admit to having terrorist motive, lawyer Kaarle Gummerus said.

"(My client) admits manslaughter and injuries... But what the investigator has brought up this far may not be enough to classify this as a terrorist crime," Gummerus told Reuters.

Mechkah appeared in court via video link from hospital, where he is being treated after being shot in the leg by police following the stabbings.

Mourners bring memorial cards, candles and flowers to the Turku Market Square. Photo: Reuters via Vesa Moilanen

The court ordered Mechkah, who has yet to be charged with any offence, to be detained in prison pending trial.

READ: Investigators believe Mechkah intentionally targeted women

Three other Moroccan men detained over possible links to the attack are due in court later on Tuesday. A fifth Moroccan who had also been under arrest was released, the court said.

The investigation is the first into suspected terrorism-related crimes in Finland's history.

Gummerus said it was "impossible to take a final stance at the moment" on the issue of whether the stabbings were terrorism-related.

Investigators have not made clear what role the three other Moroccans, who deny involvement in the attack, are suspected of playing.

Police said they had issued an international arrest warrant for a fifth Moroccan national.