Ariana Grande has said she is "broken" after the suspected terrorist attack that killed 22 people at her concert at Manchester Arena.
About 21,000 people were at the sold-out gig when the explosion happened just after 10.30pm on Monday.
Twenty-two people were killed and 59 people taken to hospital.
Grande, who was performing as part of a world tour, was unhurt but tweeted her devastation four-and-a-half hours after the explosion.
She said: "Broken. From the bottom of my heart, I am so sorry.
"I don't have the words."
Meanwhile Grande's management team, Scooter Braun Projects, said they had been left heartbroken by the incident and praised the actions of Manchester's emergency services.
They said in a statement: "Words cannot express our sorrow for the victims and families harmed in this senseless attack.
"We mourn the lives of children and loved ones taken by this cowardly act.
"We are thankful for the selfless service tonight of Manchester's first responders who rushed toward danger to help save lives.
Manchester Arena explosion
"We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers."
Police said they were treating the explosion as a terrorist attack.