BERLIN (AP) — Austrian authorities said Sunday they had foiled a possible attack on Vienna's Pride parade by three young men who had allegedly sympathized with the extremist Islamic State group.

The head of Austria's domestic intelligence service told reporters that the suspects, aged 14, 17 and 20, were arrested before the start of the Saturday's Pride parade, which was attended by around 300,000 people, public broadcaster ORF reported.

Omar Haijawi-Pirchner from the State Protection and Intelligence Directorate said that there was “no danger for the participants of the parade at any time.”

The intelligence service had received advance knowledge of the suspects’ alleged plans, kept them “under constant control,” and arrested them on the orders of the St. Poelten public prosecutor’s office following house searches on Saturday that uncovered various evidence, including weapons, ORF reported.

The three suspects, Austrian citizens of Bosnian and Chechen origin, whose identities were not further revealed, had radicalized online and sympathized with the Islamic State group, Haijawi-Pirchner said.

One of the suspects was already known to police, he added.

The trio was arrested before the start of the parade by Austria's Cobra special forces.

The organizer of the Pride parade was only informed about the events on Sunday. The organizers did not want to create panic among the participants, especially since the police raid had already taken place, according to ORF.