"Broken. From the bottom of my heart, I am so so sorry. I don't have words," she tweeted hours after a powerful blast ripped through a crowded arena hosting her concert, killing 22 people and injuring over 59 others.
According to TMZ, the singer has indefinitely suspended her world tour in the wake of the attack.
The website cited sources close to Grande, saying she has decided not to perform on Thursday in London and has also put her entire European tour on hold.
Eyewitnesses said the explosion was heard outside the auditorium after the artiste had finished her show and left the stage.
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Grande's manager Scooter Braun mourned the attack in a statement that he posted on Twitter.
"Tonight, out hearts are broken. 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 towards danger to help save lives. We ask all of you to hold the victims, their families and all those affected in your hearts and prayers," the statement read.
As part of her European tour, Grande has already performed in Birmingham and Dublin and was due to be at the O2 Arena in London tomorrow and Thursday.
Her current 'The Dangerous Woman Tour' is in support of her third studio album, 'Dangerous Woman', which released last year on May 20. The tour began on February 3, in Phoenix, Arizona.
The album is the follow-up to her 2014 studio album 'My Everything' and features guest appearances from Minaj, Lil Wayne, Macy Gray and Future. The lead single "Dangerous Woman" was released on March 11, 2016.