"All our thoughts are with the victims and the families of those who have been affected," she added.
May has also announced a temporary suspension of her campaign for her Prime Ministership, in which she faces a stiff challenge from Labor challenger and opposition leader Jeremy Corbyn.
Terrible incident in Manchester. My thoughts are with all those affected and our brilliant emergency services.— Jeremy Corbyn (@jeremycorbyn) May 22, 2017
Corbyn and Liberal Democrat candidate Tim Farron have also expressed their condolences and suspended their campaigns. For Farron, this meant canceling a planned campaign trip to Gibraltar.
My deepest condolences to the victims and families in Manchester. As always our emergency services have shown great bravery and heroism.— Tim Farron (@timfarron) May 22, 2017
On Tuesday morning, May will chair a Cabinet Office Briefing Room A (COBRA) government emergency response committee to the Manchester crisis.
More details to come