SCENE: Blast kills 22, with 59 hurt after Ariana Grande's show
American popstar Ariana Grande says she’s “broken” after 22 people were killed in a suicide bombing at a concert where she was performing in Manchester, England, on Monday night.

In a post on Twitter, the singer said she was “sorry” and didn’t have words.

The Islamic State (ISIS) has claimed responsibility for the terror attack at the Manchester Arena, which also left 59 people injured.

“One of the soldiers of the Caliphate was able to place an explosive device within a gathering of the Crusaders in the city of Manchester,” it said in a statement the group posted on its app.

Police have arrested a 23-year-old man in connection with the attack carried out late on Monday evening as about 21 000 concert-goers, mostly youngsters, began leaving the venue.

Prime Minister Theresa May said outside her Downing Street office in London yesterday: “All acts of terrorism are cowardly... but this attack stands out for its appalling sickening cowardice, deliberately targeting innocent, defenceless children and young people who should have been enjoying one of the most memorable nights of their lives."

Manchester authorities remained on high alert, while London Mayor Sadiq Khan said more police had been ordered onto the streets of the capital.

Monday’s attack was the deadliest in Britain since four British Muslims killed 52 people in suicide bombings on London’s transport system in 2005.

Witnesses said a stampede ensued following Monday night's blast.

“We ran and people were screaming around us and pushing on the stairs to go outside and people were falling down, girls were crying, and we saw these women being treated by paramedics having open wounds on their legs ... it was just chaos,” said Sebastian Diaz, 19.

US President Donald Trump described the attack as the work of “evil losers”.

The SA government has offered its commiserations, with spokesperson Nelson Kgwete saying: “President Jacob Zuma has extended his condolences to the government and the people of the United Kingdom, in particular, the families and the loved ones of those that have lost the relatives.”