Police in the south-western city of Turku have detained a man suspected of threatening officers and others with a knife on Saturday night.

Around 10.30pm emergency services received a call about a man threatening guests with a knife at a city restaurant.

Officers quickly arrived at the scene, where they were met by people running out of the establishment on Aurakatu street, according to a police statement on the incident.

Police said the officers were prepared to use force and at gunpoint, ordered the suspect to let go of the knife he was holding. The man dropped the knife to the ground enabling officers to detain him without further incident, the statement said.

Police said a preliminary investigation has been opened into the incident as a case of suspected attempted murder, due to the man having allegedly tried to stab at least one person, and suspected illegal threatening.

No injuries were reported in the incident.

Police did not specify the restaurant in which the incident began, but newspapers Iltalehti and Turun Sanomat reported that it was the fast food outlet Burger King in the Hansa shopping centre.

The investigation has involved statements from eyewitnesses, a good number of them minors.

Police noted that videos of the incident had been posted on social media.

The downtown area of Turku has seen a number of violent incidents involving young suspects in recent weeks.