Thousands of people were leaving the arena at the end of an Ariana Grande concert when the explosion ripped through the building’s foyer at around 10.35pm on Monday night, causing a stampede. Children are understood to be among those killed in the attack.
Greater Manchester police said the attack was carried out by one man, who is believed to have been carrying an improvised explosive device, which he detonated. The suspected suicide bomber died in the blast. Authorities are attempting to establish whether he worked alone or as part of a network.
Police are treating the attack as a terrorist incident, the worst in the UK since the 7/7 bombings in 2005, in which 56 people were killed in London.
The Manchester attack occurred on the fourth anniversary of the death of Fusilier Rigby, who was hacked to death in a brutal attack outside Woolwich Barracks on 22 May 2013.
Islamist extremists Michael Adebolajo and Michael Adebowale rammed the 25-year-old soldier with their car before attacking him with knives and attempting to decapitate him.
The attack sent shockwaves through Britain, with pictures of the men wielding bloodied knives captured by witnesses at the scene.
Both Adebolajo and Adebowale were jailed for life for the murder in 2014.
The deadly assault on Manchester Arena took place just two months after the Westminster attack, when Khalid Masood caused the death of five people before being shot dead by police.
Masood drove a hired car over Westminster Bridge and mounted the pavement near the Houses of Parliament before crashing into the railings outside the Palace of Westminster. He stabbed PC Keith Palmer to death after crashing the car, and killed US tourist Kurt Cochran, Romanian tourist Andreea Cristea, and Britons Aysha Frade and Leslie Rhodes.