Attacks such as the deadly bombing that killed 22 people at an Ariana Grande concert in Manchester, England were a "real fear" that was "discussed frequently" while touring in Europe, Canadian rap star Drake said Tuesday.
In a post on Instagram, the Toronto-raised rapper said he was "crushed today to hear it became a reality."
"My condolences to all of the families affected and we will be praying for all of Manchester. Also I am praying on peace of mind for Ariana," he wrote.
Monday's explosion sparked a stampede of young concertgoers, some still wearing Grande's trademark kitten ears and holding pink balloons. Authorities said an eight-year-old girl was among the dead.
Drake was one of several Canadian stars with teenage followings who voiced sympathy and solidarity Tuesday for those affected by the attack.
Teen idol Shawn Mendes, pop singers Justin Bieber and Alessia Cara, as well as YouTube star Lilly Singh all took to Twitter with messages of support.
Mendes, who is scheduled to play in Paris on Wednesday, described himself as "completely heartbroken."
"I am truly so sorry about what has happened in Manchester tonight. Unthinkable events. All my love to the families affected," he said.
"I love you so much guys. This isn't what music is about. I am so so sorry."
Cara helped circulate an online list of those still missing after Monday's show, adding "my heart is with u, Manchester."
Bieber simply tweeted the hashtag #PrayForManchester.
Singh, who was set to perform in Malaysia on Tuesday, expressed shock at the violence and urged her fans to stay strong.
"My heart and prayers go out to Ariana and everyone at her show in Manchester. I can't even imagine the feeling. No words," she tweeted.
"In a world that can be so sad and cruel sometimes, laughter really is such a gift. Shout outs to everyone who spreads love in this life."