The suicide bombing in Manchester that took 22 lives has sparked an outpouring of grief and condolences.
Here are some of the reactions:
The US pop star, who had just finished performing at an arena in the northwestern English city of Manchester, when the bomb exploded, tweeted that she was "broken" by the attack.
"From the bottom of my heart, I am so so sorry. I don't have words," the 23-year-old, who is popular with teenagers and pre-teens, wrote on her Twitter account, which has more than 45 million followers.
Grande's manager, Scooter Braun, who also represents Justin Bieber, published a longer statement on Twitter.
"We mourn the lives of children and loved ones taken by this cowardly act," the sombre black and white picture statement read. "We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers."
The US rapper, who collaborated with Grande on hits "Bang Bang" and "Side to Side" tweeted: "My heart hurts for my sister, Ariana & every family affected by this tragic event in the U.K. Innocent lives lost. I'm so sorry to hear this."
The US pop princess, a friend of Grande, tweeted: "My thoughts, prayers and tears for all those affected by the Manchester tragedy tonight. I'm sending all my love."
The US pop superstar, who is also a friend of Grande, tweeted: "Broken hearted for the families tonight. Broken hearted for Ari. Broken hearted for the state of this world."
The Oasis rocker, a Manchester native, tweeted: "In total shock and absolutely devastated about what's gone down in MANCHESTER sending Love and Light to all the family's involved LG x".
The former star of the Manchester United football team expressed his condolences via an Instagram message: "Heartbreaking news from Manchester. As a father & a human what has happened truly saddens me. My thoughts are with all of those that have been affected by this tragedy."
The US singer-songwriter, who collaborated with Grande on the soundtrack for "Beauty and the Beast", tweeted: "Sending love to the U.K., @arianaGrande and all of her supporters who were caught up in this awful attack. Heartbreaking."
Up and coming American popstar Sabrina Carpenter, who recently played in Manchester with British pop rockers The Vamps, expressed her shock. "Just played Manchester.. crazy.. really don't have words. I'm so sorry. should be a safe place. :( Thinking of all those affected," she tweeted.
"Tearing up imagining innocent concert goers losing their lives," said the US popstar. "Praying for everyone and all."
The 18-year-old British singer, who is in Cannes for the film festival, tweeted: "Incomprehensible, senseless, terrifying and beyond tragic. My heart bleeds for all those affected by #ManchesterArena".
The former guitarist for Manchester rock band The Smithstweeted: "Manchester stands together."
The British comedian, presenting "The Late Late Show" on the US television network CBS, said: "It shocks me every time we hear this sort of news, that attacks like this can happen, but especially when there will be so many children at this concert tonight.
"Many of you won’t have been to Manchester, but you will definitely have heard of it," he told US viewers.
"It’s famous all over the world for so many wonderful things - great football teams, Man City, Man United" and for "incredible music - Oasis and Joy Division."
The British pop star, a member of the One Direction boy band, tweeted: "I'm heartbroken over what happened in Manchester tonight. Sending love to everyone involved."
The US singer-songwriter tweeted: "Devastated by the news of what happened in Manchester at @arianagrande's concert. Sending my thoughts and prayers to everyone affected."
The US pop legend tweeted: "My prayers go out to ppl of Manchester... had special times there from youth and beyond."