Children have been confirmed among the dead from the Manchester concert blast, as the death toll rises to 22 and police confirm the attacker was a suicide bomber.

Greater Manchester Police confirmed about 4.10pm (AEST) that the earlier death toll of 19 had climbed, with 59 injured from the blast that ripped through an Ariana Grande concert in Manchester packed with young children about 10.35pm Monday (UK time).

Police confirmed only that the bomber used an improvised explosive device (IED) but declined to confirm earlier reports that the bomb had been a nail bomb. Police continued to treat the attack as terrorist incident until evidence suggested otherwise, and that the bomber acted alone.

“What I can confirm is that there are children among the deceased,” a police spokesman said.

“We believe at this stage that the attack last night was conducted by one man. The priority is to establish whether he was acting alone or as part of a network. The attacker, I can confirm, died at the arena.”

Police urged people not to speculate on the bomber’s details or share names.

Witnesses had earlier described the bomb as containing nails, while one witness reported finding nuts scattered throughout the foyer close to the scene of the explosion.

• Eyewitness accounts: How the terrifying events unfolded

If the bombing is confirmed as an act of terrorism, it will be the worst such attack in Britain since the 2005 suicide bombings that killed 77 people.

Watch as the explosion rips through the venue

https://twitter.com/elliefreyax/status/866830824561414145

People rush from the venue after the blast

When the explosion went off after @arianagrande concert in @ManchesterArena hope everyone is safe. #Manchester

A post shared by Zach Bruce (@zachwhiteguybruce) on May 22, 2017 at 4:06pm PDT

Desperate parents took to social media using the hashtag #ManchesterMissing to find their children, as chaos reigned after the blast.

Several social media users reported that local hotels had taken in more than 50 children who had left the stadium without guardians.

Pictures emerged on Tuesday afternoon (AEST) of relieved parents collecting their children from nearby hotels.

Foreign Minister Julie Bishop told Sky News there was no information to suggest any Australians were involved in the blast, but that enquiries were ongoing.

Prime Minister Malcolm Turnbull in Parliament on Tuesday decried the Manchester blast as an “attack on innocence”.

“This incident, this attack, is especially vile, especially criminal, especially horrific because it appears to have been deliberately directed at teenagers,” Mr Turnbull said.

“Surely there is no crime more reprehensible than the murder of children. This is a direct and brutal attack on young people everywhere, on freedom everywhere.

“We stand in this chamber offering our sympathy and support to those confronting horrific attacks like what we’ve seen today,” Mr Turnbull said.

 Opposition Leader Bill Shorten said his heart went out to the parents affected by the tragedy.

“It is to the parents that I wish to briefly speak. What makes this different to a casualty on a battlefield is that you think when your kids go to listen to music, they would be safe,” Mr Shorten said.

“My eldest two are teenagers, they go to concerts, like so many here and so many elsewhere. I can only begin to imagine the pain of parents wondering where their kids are when the first reports come out and the first texts and they realise that their family, their kids are at this concert.

“And I can only begin to dimly imagine the parents whose calls are being unanswered and the messages go through to that voicemail.”

Grande was unharmed by the incident and hours later tweeted: “Broken. from the bottom of my heart, I am so so sorry. I don’t have the words”.

TMZ reported Grande was “inconsolable” and “in hysterics” after hearing news of the fatalities and has reportedly suspended her world tour.

Prime Minister Theresa May paid tribute to the victims and families of those involved in “what is being treated by the police as an appalling terrorist attack”.

Campaigning for the June 8 election was also suspended.

A girl leaving the concert after the blast. Photo: Getty

Many of the concert-goers were young girls. Photo: Getty

Parents collect their daughter who was given refuge at a hotel near the venue. Photo: Getty

Witnesses describe pandemonium

One Grande fan who attended the concert told The New Daily that she saw police everywhere and people crying.

“We were coming out of the arena and a loud bang went off so everyone panicked. When we ran out there was lots of smoke,” the woman, who declined to have her name published, said.

“There was people with blood on them. It was so scary.”

Another concertgoer took to social media to describe the horrific scenes when the explosion occurred near her as she left the venue.

Abby Mullen spoke of being hit with blood and other matter by the blast.

Soon after police the scene, they tweeted that they would carry out a controlled blaster at the nearby Cathedral Gardens. The suspect package was later confirmed as being abandoned clothing.

The Sun‘s Tom Newton-Dunn cited hospital staff as saying the explosive device may have been a nail bomb.

“NHS [National Health Service] sources are saying the explosion at Manchester Arena was a nail bomb attack. Still unconfirmed,” he tweeted.

Manchester Arena is the largest indoor venue in Europe with the capacity to hold 21,000 people.

Crew still supporting @gmpolice @NWAmbulance at the scene of this horrific incident – please don't dial 999 unless you really need us

— Greater Manchester Fire & Rescue Service (@manchesterfire) May 23, 2017

https://twitter.com/GrantJKidney/status/866784166687494145

– with agencies