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Three men have been arrested in south Manchester in connection with the concert bomb attack, Greater Manchester Police say.

This brings the total number in custody to four.

A picture has been release of the bomber, Salman Abedi.

Frank Gardner
BBC Security Correspondent

What's worrying for security services is that this bomb marks a "complete sea change" from the low-tech attacks, such as lorry strikes, seen in continental Europe, says Frank Gardner.

The Manchester bomb involved a more sophisticated device, planning techniques such as reconnaissance, and perhaps the deliberate targeting of a US singer's concert.

"That's why the police are thinking there might be someone else involved," he says.

There is the worry that there might be an expert bomb-maker on the lose in the UK and not on the security services' radar.

The suspect's father, our correspondent says, had links to a group opposed to the Gaddafi regime in the 1990s.

People of Manchester talk of their shock and determination to unite together through their grief.

A Northamptonshire teenager who was at the Manchester Arena during Monday's suicide attack has been speaking about the confusion and fear following the explosion.

Brook Page, 17 and from Milton Malsor near Northampton, was at the Ariana Grande gig with her best friend, sister and sister's friend's family.

Image source, Brook Page

"We had just started going up the steps to leave the seated area then there was just this big bang," she told BBC Radio Northampton.

"There was a moment of complete silence in the arena, then everyone started screaming and running away. I just grabbed hold of my best friend's hand."

• Manchester attack: Latest updates

Twenty-two people died in the attack and 64 were injured; 20 are in critical care.

Describing what happened next, Brook said: "I was on the opposite side [of the arena] to the explosion, people ran to where we were, trying to get away in pure panic.

Image source, Getty Images

"When we got out to where the merchandise stands were, people were saying it was a speaker [explosion]. Then we saw a guy with blood pouring over his nose, it was all over the floor. It couldn't have been a speaker.

"The shock didn't really kick in until I got in the car. I was with my best friend and she is younger than me, so I just wanted to focus on getting her away, and my sister and her friend who was in absolute hysterics.

"We just wanted to get as far away as possible before it all sunk in."

The extra police and military presence on the streets is proportionate, says former president of the Association of Chief Police Officers Sir Chris Fox.

He was in charge of the police response to the Tube and bus bombings in London on 7 July 2005.

Image source, Other

Kelly Brewster, from Sheffield, died in the attack at the Ariana Grande concert at Manchester Arena on Monday.

Her uncle, Paul Dryhurst, said 32-year-old Ms Brewster had "heroically shielded" her 11-year-old niece from the blast in the foyer.

Read more.

Kerry Allen
BBC Monitoring, Chinese Media Analyst

Images showing the aftermath of the Manchester attack dominate Chinese papers today, even in local dailies, which are traditionally reserved for domestic stories.

Many papers prominently show pictures of crying children on their front pages. National newspaper Global Times (pictured right) headlines with “Another serious terror attack in the UK”.

Some papers however, expressed defiance against terrorism. The headline in Shanghai Morning Post (pictured left) reads: “We are still young, so the bad people should be afraid.”

Image source, BBC Monitoring

The Courteeners singer Liam Fray took a moment during his gig in Halifax last night to deliver an powerful poem in support of the victims of Monday night's attack.

Sporting an I ❤️ MCR T Shirt, Liam (pictured above with ex Manchester United captain Gary Neville) read the Manchester rallying cry, which included the words:

"We're Pankhurst and Turing, the Gallagher brothers.

"We're Morrissey, Marr and a million others!"

Watch Liam's fan shot performance below and read the poem in full underneath.

Oli Constable
BBC Local Live, Yorkshire

Around 200 people turned out to stand "shoulder to shoulder" with those affected by the bombing at the concert in Manchester on Monday night.

People laid flowers, said prayers, and had a minute's silence in memory of those killed and injured.

Among them, were three girls who had been at the concert that night.

They wore their Ariana Grande T-shirts and laid flowers in Sheffield's Peace Gardens.

Home Secretary Amber Rudd says the US has been told "it should not happen again".

Tony Walsh read a poem at the vigil for victims of Monday's attack at Manchester Arena last night as thousands of people gathered in the city's Albert Square.

In case you missed it, here it is in full.

Victoria Derbyshire

Phil and Kim Dick from Bradford are telling how they helped a bleeding 14-year-old girl they found on floor after the Ariana Grande concert.

They were waiting for their daughter and granddaughter when they saw a flash and heard an "almighty bang".

They got up from being thrown to the floor to see the chaos in the aftermath of the blast.

And they began to help the girl, who staggered towards them, bleeding and burnt.

"I held her. I just had to keep her alive," says Kim. "Telling her, 'Help's coming, you're being really brave.'"

Southport Visiter

Comedian Russell Brand has donated the proceeds, external from his stand-up gig in Southport, Merseyside last night to the victims of the Manchester Arena bombing.