Manchester , England: At least 22 people were killed and more than 50 injured in a blast on Monday at the end of a concert by U.S. singer Ariana Grande in the English city of Manchester and two U.S. officials said a suicide bomber was suspected.
Prime Minister Theresa May said the incident was being treated as a terrorist attack. If confirmed, it would be the deadliest militant assault on Britain since four British Muslims killed 52 people in suicide bombings on London's transport system in July 2005.
Police responded to reports of an explosion shortly after 10:35 pm (2135 GMT) at the arena, which has a capacity for 21,000 people, and where the U.S. singer had been performing to an audience that included many children.
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," concertgoer 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."
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.
Two U.S. officials who spoke on condition of anonymity said that initial signs pointed to a suicide bomber as being responsible for the blast .
"The choice of venue, the timing and the mode of attack all suggest this was terrorism," said a U.S. counter terrorism official who also spoke on condition of anonymity.
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. He 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.
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.”