Prime Minister Theresa May convened an emergency COBRA meeting at Downing Street on Tuesday to discuss counter-terror strategy as a male suicide bomber killed 22 persons, including children, during a concert at Manchester Arena.
Fifty nine persons were injured in the attack that occurred at 22:35 BST just as a concert by American pop singer Ariana Grande had ended.
A male suicide bomber is suspected to have carried out the attack in the foyer of the Arena building as 20,000 fans were streaming towards the exit doors.
Greater Manchester Mayor Andy Burnham and Chief Constable Ian Hopkins will attend the COBRA (a crisis response committee) meeting.
This was a major terror attack on British soil after four terrorists from Leeds killed 52 people in the London Tube and Bus on July 7, 2005. 
All major political parties suspended their election campaign on Tuesday. British Home Secretary Amber Rudd, Greater Manchester Mayor Andy Burnham, former Lord Mayor Afzal Khan were among the senior politicians who condemned the attack.
Greater Manchester Police said the lone male attacker, who died in the blast, was carrying an improvised explosive device which he detonated.
Grande was not injured, a team member confirmed.
She tweeted several hours later: “Broken. From the bottom of my heart, I am so so sorry. I don’t have words.”
Home Secretary Amber Rudd said the attack was “barbaric, deliberately targeting some of the most vulnerable”.
“This was an evil act,” said Mayor Burnham. “Our first thoughts are with the families of those killed and injured and we will do whatever we can to support them. We are grieving today but we are strong. Today it will be business as usual as far as possible in our great city.”
In a statement, the Prime Minister said: “We are working to establish the full details of what is being treated by the police as an appalling terrorist attack.
“All our thoughts are with the victims and the families of those who have been affected.”
At least 60 ambulances attended the scene of the blast, as over 240 distress calls were received. The Manchester Royal Infirmary Hospital was blocked off to all but essential staff.
No group or individual has so far claimed responsibility for the attack, but supporters of the Islamic State (IS) terror group were seen celebrating the blast on social media, the media reported.
Labour Party leader Jeremy Corbyn tweeted: “Terrible incident in Manchester. My thoughts are with all those affected and our brilliant emergency services.”
Indian Prime Minister Narendra Modi, condemning the attack said “our thoughts are with the families of the deceased and prayers with the injured”.
The US Department of Homeland Security said it was “closely monitoring” the situation.
Sir Richard Leese, leader of the Manchester City Council, said the “city will not allow terrorism to divide the communities”.
“The city has been through dark times but it’s difficult to remember anything that’s as bad as what’s happened last night,” Richard said. “We have to deal with the reality of that, at the same time as communities have to pull together with each other.
“We cannot allow what is believed to be a terror attack to divide us and we can’t allow them to win. I think that again, on the assumption that this is a deliberate attack, that the targets primarily were young girls and their families and it is almost beyond belief that anybody could target such a group of people with this appalling outrage,” Richard said.
Manchester Arena, formerly known as the MEN Arena, is the biggest indoor venue in the city with a capacity of around 18,000 for concerts.
Mancunians were showing their compassionate side just after the incident. Within an hour of reports of the blast, people began offering spare rooms and beds to people stranded in the city using the hashtag #RoomForManchester. 
Hundreds of tweets offering places to stay are being shared and re-tweeted thousands of times.
Local cab drivers were offering free rides to stranded young fans of the American diva.
Greater Manchester Police set up a hotline to help families to get details about their missing relatives – 0044 161 856 9400.
Universal Music Group, the parent company of Grande’s Republic Records label, posted on Facebook: “We are deeply saddened to learn of tonight’s devastating event in Manchester. Our thoughts and prayers are with all those affected by this tragedy.”
Musicians such as Ed Sheeran, Nicki Minaj, Katy Perry and others offered supportive tweets.
The Manchester Victoria train station located close to the Arena was shut down on Tuesday, UK National Rail announced.
In June 1996, an Irish Republic Army (IRA) truck-bomb exploded not far from the Arena that left hundreds injured.