Police said the attacker detonated the explosives shortly after 10.33 last night (22 May) at Manchester Arena, which has the capacity to hold 21,000 people. Children were among the dead, police said.
Home Secretary Amber Rudd called Britain's deadliest attack in a decade "a barbaric attack, deliberately targeting some of the most vulnerable in our society — young people and children out at a pop concert."
Following the tragedy, African leaders took to Twitter to share messages of support with the UK, and expressed their condolences.
Kenya's President Uhuru Kenyatta, whose security forces have stepped up surveillance across the country in the wake of the attack in Manchester, said in a statement: "Kenya knows what it is like to suffer a tragedy such as this, so out hearts go out to the UK."
Kenya faces threats from Somalia-based Al-Shabaab terrorists, who have previously staged deadly attacks across the country, including the 2015 Garissa University attack where 148 people were killed, and the 2013 Westgate mall attack in Nairobi in which 67 people were killed.
Highlighting how "we share a long history with the UK; we remain allies and partners", Kenyatta said he had "assured the Prime Minister, Rt Hon @theresa_may, that she will have any help we can give".
"We will stand with her and with her country in the fight against extremism," the president added.
Somalia's new president, Mohamed Abdullahi "Farmajo" Mohamed, who declared war on Al-Shabaab terrorists last month, tweeted messages of solidarity.
Nigeria's foreign minister, Geoffrey Onyeama, also shared his "heartfelt condolences", in a tweet in which he mentioned Paul Arkwright, the British High Commissioner to Nigeria. For the past seven years, terrorist sect Boko Haram has been waging a devastating insurgency in the African nation.
The head of the African Union commission Moussa Faki also shared his condolences and reiterated his support to the UK.