After a suicide bomber took 22 lives and injured more than 50 people who attended an Ariana Grande concert in Manchester, England, celebrities and fans took to Twitter to send messages of support.
Grande, who was not injured, was reportedly devastated by the attack, and has postponed her tour.
But for some fans, the incident has left them worried about another young celebrity.
Justin Bieber is scheduled to perform in England in late June and early July and his fans are already asking his manager Scooter Braun (who also manages Grande) to cancel the upcoming UK dates on the European leg of Bieber's Purpose World Tour which begins June 5.
Bieber is scheduled to appear in the UK on June 30 in Cardiff and July 2 in London. His fans expressed concern for the singer's safety when asking Braun to cancel all or part of the European tour dates.
Bieber himself has not commented on his own tour, but he has shared the trending hashtag #prayformanchester, joining a host of other concert celebs including Katy Perry, Miley Cyrus, Deborah Cox, Selena Gomez, Nicki Minaj, Justin Timberlake, Bruno Mars and many more, who offered their thoughts and prayers to Grande and concertgoers in Manchester.