GALLERY: Police identify Manchester attacker as 22-year-old

The man suspected of carrying out an attack at an Ariana Grande concert in Manchester, England, Monday that killed 22 people and injured 59 others was identified as 22-year-old Salman Abedi, police said today.

Abedi died at the scene after using an improvised explosive device, officials said. Police are still trying to determine if he acted alone or was part of a group.

The suspect was originally identified as a 23-year-old male according to a source; police have now said the suspect was 22.

Greater Manchester Police told reporters earlier that 23-year-old man was arrested in South Manchester in connection with the attack.

Greater Manchester Police are requesting dashcam footage from “anyone who was in Manchester city centre” between 8 p.m. and 11 p.m. Monday night as part of their investigation.

ISIS has claimed responsibility for the explosion. In a statement translated from Arabic, ISIS said that a “soldier of the caliphate” placed explosives at a gathering of “crusaders” — meaning Christians — at the Manchester Arena. The statement said about 30 people were killed and about 70 more were wounded.

The explosion is being treated as a terrorist attack, and U.K. Prime Minister Theresa May said the threat level remains at severe, meaning the government considers another attack highly likely. The severe level is the second highest of five, with critical the highest.

Police also said authorities executed two warrants as a part of the investigation: one in the Whalley Range district of Manchester and one in the Manchester suburb of Fallowfield, where a controlled explosion took place.

Greater Manchester Police said officers were called to the Manchester Arena just before 10:35 p.m. local time on Monday. The explosion happened near the arena’s foyer after the concert, according to witnesses, who reported hearing a bang as they exited.

An 8-year-old girl named Saffie Rose Roussos is among those killed.

The venue holds about 21,000 people and is one of Europe’s largest indoor arenas, according to its website. The arena is connected to the Manchester Victoria Station, the city’s second-largest train station.

An 8-year-old girl named Saffie Rose Roussos is among those killed.

Twelve children under the age of 16 were seriously injured, officials said.

“We struggle to comprehend the warped and twisted mind that sees a room packed with young children not as a scene to cherish but as an opportunity for carnage,” May said Tuesday.

Witness Joseph Harries told ABC News’ “Good Morning America” that “people were just trying to get out of the arena as fast as they possibly could after the blast. I was directly in front of the stage at the heart of the arena. I had exactly the same distance to get out of any of the doors.”

“I had my best friend with me and I grabbed hold of her wrist and told her never let go of me,” Harries said. “We just ran, we jumped over chairs, railings to get out of the doors, we had to force open doors that wouldn’t open because people were trying to get to – the entire capacity of the 20,000 person arena were trying to get out of one exit.”

“It felt like an eternity,” Harries said, but it “couldn’t have been more than two, three minutes from in our seats to outside of the arena.”

The Greater Manchester Police tweeted today that officials do not believe there are any unaccompanied children at Manchester-area hotels.

A U.S. State Department official told ABC News today that the “U.S. Embassy in London is working to determine if any U.S. citizens were affected,” adding, “at this time, we are not aware of any U.S. citizens killed or injured.”

“The whole nation has been shocked,” Queen Elizabeth II said in a statement. “I know I speak for everyone in expressing my deepest sympathy to all who have been affected by this dreadful event and especially to the families and friends of those who have died or were injured.”

“I want to thank all the members of the emergency services, who have responded with such professionalism and care,” the queen continued. “And I would like to express my admiration for the way the people of Manchester have responded, with humanity and compassion, to this act of barbarity.”

A spokesperson for the Manchester Arena tweeted today, “Last night, our community suffered a senseless tragedy. Our entire team’s thoughts and focus are now on supporting the people affected and their families.

“We are assisting the police in any way we can. We cannot praise the emergency services enough for their response and have been inspired by the way the people of this great city of Manchester rallied round last night and have continued to respond today. It shows the very best of this city.”

ABC News’ Mike Levine and Lena Masri contributed to this report.