GENEVA, May 28 (Xinhua) -- Swiss authorities said on Thursday a stabbing attack at Winterthur train station near Zurich that wounded three people was an "act of terrorism."

The incident occurred at around 8:30 a.m. (0630 GMT). One person sustained serious injuries, while the other two suffered moderate injuries, according to police.

Mario Fehr, security director for canton of Zurich, described the incident as an "act of terrorism." "I previously used this term when describing the attack on an Orthodox Jew in Zurich-Wiedikon," he told a press conference.

Fehr said the 31-year-old suspect, who was arrested shortly after emergency services were alerted, was born in Switzerland in 1994 and became a Swiss citizen in 2009. However, the suspect moved to Trkiye in 2024 and returned to Switzerland in May 2026.

According to authorities, the suspect had recently been treated at a psychiatric clinic and was released on Wednesday. "At the clinic, it was decided that he posed no danger to others or to himself," Fehr said. "That was clearly an error of judgment."

Swiss President Guy Parmelin said on social media he was "shocked by the terrorist attack this morning in Winterthur."

"This deeply affects me," he added.