ZURICH, - A knife attack at a Swiss train station that left three people injured was an act of terrorism, police said on Thursday, after arresting a suspect who had previously been reported for spreading Islamic State propaganda.Police said they had arrested the alleged ‌perpetrator, a 31-year-old ⁠dual Swiss-Turkish ⁠national, from Winterthur, a city to the north of Zurich. The attack ​took place at around 0630 GMT.Mario Fehr, security director for the canton of ​Zurich, described the attack as "a vile terrorist act which I believe was handled very well by the police, who were able to ​prevent something even worse from happening."Fehr, speaking ⁠at a ‌press conference, praised a teacher who stood in ​front of ​her pupils to protect them before the man ⁠was arrested."There were various brave people," Fehr said, including ​the teacher who "behaved in an exemplary fashion".Zurich cantonal ​police commandant Marius Weyermann said the suspect had previously been reported to the police in 2015 for spreading propaganda from the hardline militant group Islamic State."The motive for this act must be sought in the area of radicalization and extremism," Weyermann said.Swiss ‌newspaper Blick said it had obtained a video showing a man running out of the concourse of Winterthur ​station shouting "Allahu ​Akbar", an Arabic ⁠phrase that translates as "God is greatest".Reuters did not independently verify the video.The three victims of the attack were receiving hospital care, according to ​the police. One person was stabbed in the leg, another in the neck, while a third man was stabbed in the thigh.The injured were taken to hospital, with the third man needing emergency surgery for his injuries, Weyermann said.