<sod >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. 'We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers.' Nineteen people died after the blast tore through crowds leaving the pop concert, with dozens of others injured in the explosion.  Insiders told TMZ that Grande's concert scheduled for Thursday at London's O2 Arena could be cancelled because she was 'in no condition to perform,' in addition to ongoing security concerns.< eod>< sod > 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. 'We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers.' A sign saying 'Ariana we love you' was left in the street nearby the arena. Theresa May said 'many children' were among the victims Nineteen people died after the blast tore through crowds leaving the pop concert, with dozens of others injured in the explosion.  Insiders told TMZ that Grande's concert scheduled for Thursday at London's O2 Arena could be cancelled because she was 'in no condition to perform,' in addition to ongoing security concerns.< eod>