At least 22 people were killed in an explosion at a concert in Manchester, United Kingdom, BBC reported. The blast took place on Monday night while American singer Ariana Grande was performing at the arena. The attacker is believed to have been killed in the blast, the Greater Manchester Police told BBC. They said he detonated the explosive device that he was carrying with him.

At least 59 people were injured in the incident that took place “outside the venue in a public space”, reported The Guardian. A spokesperson for the musician said she was “okay”. The audience is believed to have included a large number of youngsters.

The local police found another explosive device at the venue only hours after the explosion. However, they managed to carry out a controlled explosion and avoided further casualties.

“We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming,” concert-goer Catherine Macfarlane told Reuters. “It was a huge explosion – you could feel it in your chest. It was chaotic. Everybody was running and screaming and just trying to get out.”

Manchester Arena is the largest indoor arena in Europe and it has a capacity for 21,000 people. It is popular for hosting concerts and sporting events.