Organizers of three Taylor Swift concerts in Vienna have called off the shows after officials announced arrests over an apparent plot to launch an attack on an event in the area such as the concerts. Swift was scheduled to play at the Austrian capital's Ernst Happel Stadium on Thursday, Friday and Saturday. The event organizer said "We have no choice but to cancel the three scheduled shows for everyone's safety." Authorities say they have arrested two suspected extremists. One had pledged allegiance to ISIS and is believed to have become radicalized on the internet.