Taylor Swift's canceled concert: Officials found explosives, detonators, and a stockpile of chemicals in a 19-year-old's home

• Officials said a 19-year-old male planned to use knives and explosives at a Taylor Swift concert.
• He and another 17-year-old male are believed to have been radicalized by ISIS, authorities said.
• They were in contact with other people who knew about the attack, an Austrian official said.

Austrian officials said they arrested three male teenagers on Wednesday on suspicion of planning an attack on a Taylor Swift concert in Vienna, the threat of which prompted organizers to cancel three of the singer's shows.

The main suspect, a 19-year-old Austrian citizen, was arrested in the town of Ternitz, about 30 miles from Vienna, said the head of the Directorate of State Security and Intelligence, Omar Haijawi-Pirchner.

Haijawi-Pirchner said at a news conference on Thursday that the suspect was planning a suicide attack with knives and explosives that would kill "as many people as possible" at the concert.

Officials said they found explosives, detonators, and chemicals in the 19-year-old's home, and that he'd been researching bomb-making techniques.

The young man was "clearly radicalized" by the Islamic State and had posted an oath of allegiance to the terrorist organization's leader, Haijawai-Pirchner said.

He is cooperating with authorities and fully admitted to the plot, Haijawi-Pirchner added.

Franz Ruf, the director-general for public safety in the Ministry of the Interior, said the suspect had planned the attack since July and has North Macedonian roots.

The other two teenagers arrested were a 15-year-old and a 17-year-old. The 17-year-old has refused to speak with authorities, who found Islamic State and Al-Qaeda propaganda in his home.

The Austrian citizen, who has Turkish and Croatian roots, worked for a facilities company that was contracted to provide services at the concert venue. Authorities didn't say what services these were.

Officials said he'd just broken up with his girlfriend and was seized outside the concert stadium.

Neither the 19-year-old nor the 17-year-old had tickets to the shows, authorities added.

Little information was provided on the 15-year-old, whom authorities said was also questioned by police.

Ruf said the three suspects were in contact with other people who knew about the planned attack, but that authorities aren't looking for any other suspects.

Interior Minister Gerhard Karner said foreign intelligence agencies helped uncover the plot, which led concert organizers to cancel the Eras Tour shows on Wednesday.

Some stunned fans had already arrived from other continents for the concerts scheduled for Thursday, Friday, and Saturday.

In lieu of the concert, scores of fans gathered near the venue on Thursday to sing Swift's songs as police looked on.

Ewald Tatar, the head of concert organizer Barracuda Music, said at a press conference that the shows had been canceled for the safety of concert-goers and those outside the stadium.

Tatar expected crowds of up to 15,000 people to gather in the hours before the shows began, which would build to nearly 100,000 people inside and outside the stadium before Swift took the stage.

"I have to say that, despite everything, I am very happy with this decision," Tatar told reporters, saying management had made the "right" choice.

Barracuda Music has said all tickets will be refunded within 10 days.

Europe has been on high alert for ISIS-related attacks on pop concerts, after several mass attacks were carried out by the group, including a bombing in Manchester that killed 22 people at an Ariana Grande concert in 2017.