The Austrian authorities announced today, Friday, that a third person has been arrested in connection with the failed plot to attack three Taylor Swift concerts, which have now been canceled, even as frustrated fans enchant Vienna by exchanging friendship bracelets and singing the pop star's songs in the streets.

The main suspect, a 19-year-old, was planning to target spectators gathered outside the Ernst Happel Stadium - up to 30,000 people each night, with another 65,000 inside the venue - with knives or homemade explosives during the concert on Thursday or Friday. Authorities said the suspect hoped to "kill as many people as possible."

Officials said the main suspect, 19, was arrested on Tuesday, along with a 17-year-old male. Both are Austrian citizens.

On Friday, the interior minister said at an unrelated press conference that the third suspect, an 18-year-old Iraqi national, was apprehended Thursday evening.

A 15-year-old boy was also questioned but has not been arrested. Their names have not been disclosed, in accordance with Austrian privacy laws.

Swift is still scheduled to travel to Wembley Stadium in London for five concerts between August 15 and 20, closing out the European leg of her record-breaking Eras tour.

London Mayor Sadiq Khan said that while he understands Vienna's reasons for the cancellation, "we will carry on."

However, the Vienna plot has been compared to a 2017 attack by a suicide bomber at Ariana Grande's concert in Manchester, England, which killed 22 people. The bomb exploded at the end of Grande's concert as thousands of young fans were leaving, becoming the deadliest extremist attack in the UK in recent years.

Coldplay is set to perform four nights at the same Vienna venue later this month.

Authorities said the plot was inspired by ISIS and al-Qaeda. The main suspect, as well as the 18-year-old arrested on Friday, pledged an "oath of allegiance" to ISIS.

Investigators found materials for making bombs in the main suspect's home, along with materials related to ISIS and al-Qaeda in the 17-year-old's residence. The suspect, who has so far declined to speak, had been working a few days prior at a company providing unspecified services at the concert venue.

Although the 18-year-old took the oath and "comes from the social environment" of the main suspect, Interior Minister Gerhard Karner stated that he is not directly linked to the plot.

The Austrian Interior Ministry, in a statement to the Associated Press on Friday, said, "His arrest confirms the broad scope of the ongoing investigation. Authorities are taking decisive action against anyone who may be involved in terrorist activities or shows extremist tendencies."

The statement said investigators are examining the suspects' "networks" and have turned to assessing physical and electronic evidence.

Shiraz Maher, an expert in Islamist extremism at King's College London, stated in a statement to the Associated Press that attackers "prioritize victims and therefore choose soft targets where they know large numbers of people will gather."

Concert promoter Barracuda Music said it canceled the three-night Eras tour, originally scheduled to start Thursday, because the arrests were too close to the show date.

Heartbroken Swifties consoled each other on social media and in the streets of Vienna. After traveling from around the world, hundreds gathered on Corneliusgasse, a small street just 5 kilometers (3 miles) from the stadium, which shares its name with "Cornelia Street," a reflective synth-pop track from Swift's 2019 album, "Lover."

They sang along to Swift's greatest hits, took selfies, and exchanged friendship bracelets. Swift fans often exchange bead bracelets, which typically feature Swift song titles or famous phrases, with strangers at her concerts.

Even as fans sang her lyrics, the star has not publicly commented on the plot or the concert cancellations. The "Taylor Nation" page, a verified Instagram account widely believed to be managed by her team, reposted Barracuda Music's announcement, while her main account has posted nothing.

Last month, when a suspect in England killed three girls and injured 10 people in a knife attack during a dance and yoga lesson themed after Taylor Swift, the artist said she was "completely shocked" by the violence.