By Michael Holden and Andrew Yates
UPDATE 9:40a 5/23/17: ISIS has claimed responsibility for the deadly explosion at an Ariana Grande concert in Manchester, England, Monday that killed 22 people and injured 59 others.
In a statement translated from Arabic, ISIS said that a soldier of the caliphate placed explosives among a gathering of crusaders -- meaning Christians -- at the Manchester Arena. The statement said about 30 were killed and about 70 were wounded.
The man believed to be the lone attacker died at the scene after using an improvised explosive device, officials said, but police are still determining if the attacker acted alone or as part of a wider group, said United Kingdom Prime Minister Theresa May.
MANCHESTER, England (Reuters) - At least 22 people, including some children, were killed and 59 wounded when a suicide bomber struck as thousands of fans streamed out of a concert by U.S. singer Ariana Grande in the English city of Manchester on Monday.
Prime Minister Theresa May said the incident was being treated as a terrorist attack, making it the deadliest militant assault in Britain since four British Muslims killed 52 people in suicide bombings on London's transport system in July 2005.
Police said the attacker detonated the explosives shortly after 10:33 pm (2133 GMT) at Manchester Arena, which has the capacity to hold 21,000 people. Children were among the dead, police said.
"We believe the attacker was carrying an improvised explosive device which he detonated causing this atrocity," said Hopkins, who declined to answer questions about whether the attacker was British.
The explosion occurred shortly after Grande left the stage at the arena, which has a capacity of around 21,000. Grande has a strong following among teenage girls and children
A witness who attended the concert said she felt a huge blast as she was leaving the arena, followed by screaming and a rush by thousands of people trying to escape the building.
A video posted on Twitter showed fans, many of them young, screaming and running from the venue. Dozens of parents frantically searched for their children, posting photos and pleading for information on social media.
"We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming," concert-goer Catherine Macfarlane told Reuters.
"It was a huge explosion - you could feel it in your chest. It was chaotic. Everybody was running and screaming and just trying to get out."
Ariana Grande, 23, later said on Twitter: "broken. from the bottom of my heart, i am so so sorry. i don't have words." May, who faces an election in two-and-a-half weeks, said her thoughts were with the victims and their families. She and Jeremy Corbyn, the leader of the opposition Labour Party, agreed to suspend campaigning ahead of the June 8 election.
"We are working to establish the full details of what is being treated by the police as an appalling terrorist attack," May said in a statement. "All our thoughts are with the victims and the families of those who have been affected."
May is due to hold a crisis response meeting and finance minister Philip Hammond will cut short a trip to Brussels to return to London.
Chinese President Xi Jinping sent his condolences to Queen Elizabeth while French President Emmanuel Macron said he would discuss the fight against terrorism with May.
There was no immediate claim of responsibility, but U.S. officials drew parallels to the coordinated attacks in November 2015 by Islamist militants on the Bataclan concert hall and other sites in Paris, which claimed about 130 lives.
British police were on alert for any further attacks. Central London's Victoria coach station and roads around it were closed after discovery of a suspect package, the BBC said.
Islamic State supporters took to social media to celebrate the blast and some encouraged similar attacks elsewhere.
Britain is on its second-highest alert level of "severe", meaning an attack by militants is considered highly likely.
British counter-terrorism police have said they are making on average an arrest every day in connection with suspected terrorism.
In March, a British-born convert to Islam ploughed a car into pedestrians on London's Westminster Bridge, killing four people before stabbing to death a police officer who was on the grounds of parliament. The man was shot dead at the scene.
In 2015, Pakistani student Abid Naseer was convicted in a U.S. court of conspiring with al Qaeda to blow up the Arndale shopping center in the center of Manchester in April 2009.
broken.— Ariana Grande (@ArianaGrande) May 23, 2017
from the bottom of my heart, i am so so sorry. i don't have words.
Manchester Arena, the largest indoor arena in Europe, opened in 1995 and is a popular concert and sporting venue.
Desperate parents and friends used social media to search for loved ones who attended Monday's concert while the wounded were being treated at six hospitals across Manchester.
"Everyone pls share this, my little sister Emma was at the Ari concert tonight in #Manchester and she isn't answering her phone, pls help me," said one message posted alongside a picture of a blonde girl with flowers in her hair.
Paula Robinson, 48, from West Dalton about 40 miles east of Manchester, said she was at the train station next to the arena with her husband when she felt the explosion and saw dozens of teenage girls screaming and running away from arena.
"We ran out," Robinson told Reuters. "It was literally seconds after the explosion. I got the teens to run with me."
Robinson took dozens of teenage girls to the nearby Holiday Inn Express hotel and tweeted out her phone number to worried parents, telling them to meet her there. She said her phone had not stopped ringing since her tweet.
"Parents were frantic running about trying to get to their children," she said. "There were lots of lots children at Holiday Inn."