Three Taylor Swift concerts this week in Vienna have been cancelled following arrests over an apparent plot to launch an attack in the area, potentially at the stadium itself, and at least one of the suspects has been linked to the Islamic State group.

Chemical substances and technical devices were found at the house of that suspect, a 19-year-old Austrian, according to Franz Ruf, the public security director at Austria's Interior Ministry.

In an interview Thursday with public broadcaster ORF's Oe1 program, Ruf said investigators are evaluating the evidence seized from the suspect's home. Just a few weeks ago, the 19-year-old had uploaded an oath of allegiance to the current leader of the Islamic State group militia to an internet account, Ruf added.

A second person was arrested in the Austrian capital. Several Austrian media reported Thursday that additional suspects were being sought -- something police did not officially confirm.

The cancellations devastated Swifties across the globe, many of whom had dropped thousands of euros on travel and lodging in Austria's expensive capital city for the sold-out Eras Tour shows on Thursday, Friday and Saturday at the Ernst Happel Stadium, which sat empty Thursday morning aside from media filming outside.

Europe is enamoured by the American superstar, with the German town of Gelsenkirchen renaming itself “Swiftkirchen” before its mid-July concerts.

Austria's Vice-Chancellor Werner Kogler wrote on social platform X: “For many, a dream has been shattered today. On three evenings in Vienna, tens of thousands of #Swifties should have celebrated life together.”

“I am very sorry that you were denied this. Swifties stick together, hate and terror can't destroy that,” Kogler wrote late Wednesday.

Ruf said authorities were aware of “preparatory actions” for a possible attack “and also that there is a focus by the 19-year-old perpetrator on the Taylor Swift concerts in Vienna,” the Austria Press Agency reported.

The Austrian citizen is believed to have become radicalised on the internet. Ruf didn't give more details, such as the suspects' names, in line with Austrian privacy law.

Event organiser Barracuda Music said in an Instagram post late Wednesday that “we have no choice but to cancel the three scheduled shows for everyone's safety". It cited government officials' confirmation of a planned attack at the stadium.

The cancellation came hours after authorities said security measures for the Swift concerts would be stepped up. Ruf previously said that there would be a special focus among other things on entry checks, and concertgoers should plan a bit more time.

Vienna Police Chief Gerhard Pürstl said at the same time that, while any concrete danger had been minimized, an abstract risk justified raising security.

Austrian Chancellor Karl Nehammer posted on X that “the cancellation of the Taylor Swift concerts by the organizers is a bitter disappointment for all fans in Austria".

“The situation surrounding the apparently planned terror attack in Vienna was very serious,” he wrote. But he added that, thanks to intensive cooperation between police and Austrian and foreign intelligence, “the threat could be recognized early on, tackled and a tragedy prevented".

Barracuda Music said that “all tickets will be automatically refunded within the next 10 business days". The same wording was posted under the Vienna dates on Swift's official website.

The Vienna stadium had been sold out for the planned concerts, APA reported, with an estimated 170,000 fans expected for the concerts in Austria.

Some who posted on X lamented months of now-wasted efforts to make friendship bracelets and pick out fashionable outfits for the performance.

The cancellations came more than a week after a stabbing attack in the northwest England seaside town of Southport during a Taylor Swift-themed summer holiday dance and yoga class. The violence left three girls dead and 10 others injured. A 17-year-old has been charged with murder.

In 2017, an attack at an Ariana Grande concert in Manchester, England, killed 22 people. Suicide bomber Salman Abedi set up a knapsack bomb in Manchester Arena at the end of Grande's concert as thousands of young fans were leaving. More than 100 people were injured. Abedi died in the explosion.

An official inquiry reported in 2023 that Britain's domestic intelligence agency, MI5, didn't act swiftly enough on key information and missed a significant opportunity to prevent the bombing, the deadliest extremist attack in the United Kingdom in recent years.