ISIS has claimed responsibility for the attack. The explosion happened in the foyer of the arena as the concert was ending just after 10:30, witnesses said. The Manchester Arena, which has more than 20,000 seats, is one of the largest indoor venues in Europe, according to its website.
She released a longer statement on May 26.
Grande's manager, Scooter Braun, also released a statement on Twitter saying, "Words cannot express our sorrow for the victims and families harmed in this senseless attack."
Other celebrities including Ryan Seacrest and Cher took to social media to express their shock and condolences.
Many of the concert-goers were groups of young people, United Kingdom Prime Minister Theresa May said.
"This attack stands out for its appalling, sickening cowardice, deliberately targeting innocent, defenseless children and young people who should have been enjoying one of the most memorable nights of their lives," she said.