Two people have been stabbed to death in the street in Finland. Six others were injured and taken to hospital after the knife attack in the city of Turku, according to the police.

The motive is not known. The police say a suspect was arrested after a shootout. Security is being reinforced nationwide – including at Helsinki airport and train stations – with additional patrols and surveillance stepped up.

People were warned to stay away from the southern city, 170 kilometres west of Helsinki following the attack in one of Turku’s main squares.

Police said they were continuing to look for potential accomplices – even though the young man being held was the only suspect so far.

They added that it was unclear whether the attack was related to terrorism. Security services raised Finland’s terror threat level in June.

The Finnish Security and Intelligence Service raised the country’s terrorism threat level in June.