The incident occurred on early Thursday afternoon when city police received information that “dangerous people” were in the cars, Marto Cortesi, Zurich city police spokesman told The Local.

“We had some information about two cars and three people,” Cortesi said.

“We had some information that dangerous people were in these cars.”

Cortesi said he could not go into details about what specific danger was suspected but he said city and cantonal police were jointly involved in the arrest, which he acknowledged was “a mistake”.

Witnesses told 20 Minuten that at least 10 officers surrounded the vehicles wielding guns, including a machine gun.

“Then the men were dragged out and handcuffed,” an onlooker told the newspaper.

“The action was indeed spectacular but the arrests happened quietly,” another witness told 20Minuten.

“The (arrested) men did not resist.”

The Swedes were taken to a local police station but were released after “five minutes,” when police realized the information they had received was false, police spokesman Cortesi told The Local.

Police apologized to the Swedes, who were tourists visiting Switzerland, he said.