THE suicide bomber who killed 22 people and injured 59 more at an Ariana Grande concert in Manchester was a university dropout who may have made secret trips to Syria to train for the attack.
The young man, named by British police as Salman Abedi, exploded a homemade bomb and died inside Manchester Arena at the end of the US pop star's performance on Monday night.
UK police revealed, Mr Abedi was a 23-year-old British national of Libyan descent.
- BOOTS ON THE GROUND: UK fears 'imminent' terror attack
- Homeless man 'pulls nails out of girl's face' after attack
- Viral symbol marks bravery of teenage fans caught in blast
- Angry, not scared: Coast man on streets of Manchester
- FOOTAGE: The moment of the concert explosion
He was born in Manchester and grew up alongside three siblings.
British intelligence agents are investigating reports the football-obsessed Abedi slipped into Syria while visiting relatives in Libya several times in recent years, The Sun reports.
His home in the Manchester suburb of Fallowfield was one of two that police raided in relation to the attack on Tuesday.
Neighbours say Abedi, who studied business and management at Salford University before dropping out, had grown a beard in the last 12 months and had begun acting strangely.
"A couple of months ago he [Salman] was chanting the first kalma [Islamic prayer] really loudly in the street. He was chanting in Arabic," Lina Ahmed told The Sun.
"He was saying 'There is only one God and the prophet Mohammed is his messenger'."
Another neighbour, Leon Hall, said the young man "had an attitude problem."
British Prime Minister Theresa May said Abedi deliberately chose to detonate an explosive at the end of the show to inflict "maximum carnage."
Islamic State has claimed responsibility for the bombing, but Chief Constable Ian Hopkins said it was not clear yet how many other people were involved in the planning.
"Our priority, along with the police counterterrorist network and our security partners, is to continue to establish whether he was acting alone or working as part of a wider network," he said Tuesday afternoon.
Theresa May said the attack was among "the worst terrorist incidents" in UK history.
"A single terrorist detonated his improvised explosive device near one of the exits of the venue, deliberately choosing the time and place to cause maximum carnage and to kill and injure indiscriminately," she said outside her official residence at 10 Downing St, London.
"It is now beyond doubt that the people of Manchester and of this country have fallen victim to a callous terrorist attack, an attack that targeted some of the youngest people in our society with cold calculation.
"As so often, while we experience the worst of humanity in Manchester last night, we also saw the best.
"The cowardice of the attacker met the bravery of the emergency services and the people of Manchester.
"Let us remember those who died and let us celebrate those who helped safe in the knowledge that the terrorists will never win and our values, our country and our way of life will always prevail."
Police said the blast occurred in the foyer of the 21,000-capacity indoor arena, a covered area which links to Victoria railway station.
Some concertgoers mistook the massive bang for exploding balloons, which had been dropped onto the crowd at the end of the performance.
The bomb sent nuts and bolts flying, witnesses said, and bloodied bodies were strewn across the floor after the blast about 10.30pm Monday (7.30am Tuesday, Australian eastern standard time). Some fans were trampled as panicked crowds tried to flee the venue.
"There was an explosion heard as we were leaving the arena and then another one when we got outside," concertgoer Sibion Joyce, from Bury in Greater Manchester, told news.com.au.
"Everyone went still at first and then the panic kicked in and people started running and screaming to get out of the arena, there were lots of young people.
"I was scared, at first we didn't think it was anything as serious as this but when the swarms of emergency services arrived it was evident it was a serious incident."
The 22-year-old added: "I was trying to get home from Manchester for two hours, there is a three-mile radius cordoned off."
Update your news preferences and get the latest news delivered to your inbox.