Leaders from around the world have condemned the terror attack at a Manchester music concert and offered their condolences to the victims.
:: US president Donald Trump, speaking during a visit to Bethlehem, in the Palestinian West Bank, said: "I extend my deepest condolences to those so terribly injured in this terrorist attack and to the many killed and the families, so many families, of the victims.
"We stand in absolute solidarity with the people of the United Kingdom."
Mr Trump said "many young, beautiful, innocent people" had been "murdered by the evil losers in life".
He added: "I won't call them 'monsters', because they would like that term. They would think that a great name.
"I will call them from now on 'losers', because that is what they are."
Mr Trump said civilised societies should have "no tolerance" for continued bloodshed of this kind.
"The terrorists and extremists and those who give them aid and comfort must be driven out from our society forever," he said.
"This wicked ideology must be obliterated and I mean completely obliterated."
:: German chancellor Angela Merkel said she was following the news from Manchester "with sorrow and horror" and offered her "deep sympathy" to all those affected.
"It is incomprehensible that someone could make use of a joyful pop concert to bring death to so many people or inflict serious injury on them," she said.
"This apparent terrorist attack will only strengthen our determination to keep acting together with our British friends against those who plan and carry out such inhuman deeds.
"I assure people in Britain: Germany stands by your side."
:: French president Emmanuel Macron said: "My thoughts are with the British people, the victims and those close to them. We are fighting together against terrorism."
The Elysee Palace said Mr Macron would be speaking with Theresa May by telephone about the ongoing investigation.
:: The Kremlin released a statement on behalf of Russian president Vladimir Putin, saying he had "expressed his condolences to the British prime minister following (the) Manchester bomb attack".
:: The President of the European Commission, Jean-Claude Juncker, said: "It was with great sadness and profound shock that I learnt of the brutal attack that struck Manchester.
"It breaks my heart to think that, once again, terrorism has sought to instil fear where there should be joy, to sow division where young people and families should be coming together in celebration.
"I would like to convey my deepest sympathies to Prime Minister May and to the British people.
"Today we mourn with you. Tomorrow we will work side by side with you to fight back against those who seek to destroy our way of life.
"They underestimate ours and your resilience, these cowardly attacks will only strengthen our commitment to work together to defeat the perpetrators of such vile acts."
:: The President of the European Council, Donald Tusk, tweeted: "My heart is in Manchester this night. Our thoughts are with the victims."
:: Australian prime minister Malcom Turnbull told the country's parliament the incident was a "brutal attack on young people everywhere".
He said: "This incident, this attack, is especially vile, especially criminal, especially horrific because it appears to have been deliberately directed at teenagers.
"This is an attack on innocents. Surely there is no crime more reprehensible than the murder of children.
"This is a direct and brutal attack on young people everywhere, on freedom everywhere."
:: Indian prime minister Narendra Modi tweeted: "Pained by the attack in Manchester. We strongly condemn it. Our thoughts are with the families of the deceased & prayers with the injured."
:: In Japan a government spokesman said: "If this is a terrorist attack, such abhorrent acts of terrorism cannot be justified for any reason, and Japan firmly condemns such an act of terrorism.
"I would like to express my heartfelt condolences to the victims and families of the deceased and my prayers to a swift recovery for the wounded. Japan stands in solidarity with the people of the UK."
:: Canadian prime minister Justin Trudeau tweeted: "Canadians are shocked by the news of the horrific attack in Manchester tonight. Please keep the victims & their families in your thoughts."
:: US First Lady Melania Trump wrote on Twitter: "My thoughts and prayers to the families of #Manchester."
:: French prime minister Edouard Philippe said: "The most cowardly form of terrorism has struck once more, targeting, as it did in Paris more than a year ago, a concert venue, aimed specifically and knowingly at very young girls gathered together for a moment of celebration and joy.
"In the wake of this abominable crime, I would like to express my sadness, the solidarity of the French people and unwavering friendship to Mancunians and all British people."