Among the celebrities who mourn for the victims of the Paris terror attacks is Canadian singer and songwriter Justin Bieber.

The 21-year-old star paid a touching tribute to his friend Thomas Ayad through Twitter on Monday evening, as reported by People.

According to Gossip Cop, Thomas Ayad was in Bataclan Theater for the Eagles of Death Metal when the attackers fired gunshots. Ayad was an executive for Universal Music Group. He had recently worked for the sub-label Mercury Records. UMG chairman and CEO Lucian Grainge confirmed that Ayad was one of the people who died in the theater.

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"Still thinking about Paris and my friend Thomas that we lost in the tragedy. He was a part of the team for years and I wish I would've had more time to thank him," Beiber wrote on his Twitter account.

He added, "Make sure to appreciate people while you have them. Thanks Thomas for everything you did for me. You are appreciated and missed. Thoughts and prayers are with your family & friends #PrayForParis."

Hours after the attacks, Bieber also broke down during a concert to promote his new album in Staples Center in Los Angeles. The singer was reportedly set to perform three shows. A previous report by Gossip Cop said the singer learned about the tragedy after the first show. In his second show, he became emotional after singing "I'll Show You."

"We're all in this together." Bieber told the crowd and then said to himself, "Why am I crying so hard? Get it together, Justin!"

The singer was scheduled to be interviewed by "Today" on Monday. However, it was postponed to Wednesday out of respect for NBC's ongoing coverage of the situation in Paris.

More than a hundred people died in the Paris attacks. ISIS has claimed responsibility for the brutal crime.

TagsJustin Bieber, Paris Attacks, #PrayforParis, Purpose, mourning