WATCH: Police update on Manchester explosion that killed 22 people

Police in Manchester, UK say 22 people were killed after a reported explosion Monday night at the city’s arena, where pop star Ariana Grande was performing. Twelve children under age 16 were among the additional 59 injured.

Authorities are expected to provides updates past 1 p.m. ET today on the Manchester explosion that killed 22 people and injured dozens more at the end of an Ariana Grande concert Monday.

The explosion, which occurred around 10:33 p.m. local time, led to mass panic among concertgoers and is being treated as a terrorist attack “until police know otherwise,” the Manchester Police reported on Twitter. Police say they have arrested a 23-year-old man in South Manchester in connection to the attacks.

Manchester’s Chief Constable Ian Hopkins said early Tuesday that a man had detonated an improvised device. The Islamic State has claimed responsibility, the Associated Press reports.

Prime Minister Theresa May addressed the nation in a televised speech Tuesday morning. “We now know that a single terrorist detonated his improvised explosive device near one of the exits of the venue, deliberately choosing the time and place to cause maximum carnage and to kill and injure indiscriminately,” she said.

“All acts of terrorism are cowardly attacks on innocent people, but this attack stands out for its appalling, sickening cowardice, deliberately targeting innocent, defenseless children and young people who should have been enjoying one of the most memorable nights of their lives,” May, who traveled to Manchester after the speech, said.

The Queen expressed her “deepest sympathy” in addition to her “admiration for the way the people of Manchester have responded, with humanity and compassion, to this act of barbarity.”

In Bethlehem, President Donald Trump branded those who carried out the attack “evil losers.” “We stand in absolute solidarity with the people of the United Kingdom,” he said on Twitter.

Grande was not injured, AP reports, citing a representative of the singer’s record label. The performance Monday was part of an international tour that included two additional shows in London later this week.

The incident occurred at about 10:30 p.m., as the show was ending. Some fans took to Twitter to share video they said was taken inside the arena; giant pink balloons were tousled above the crowds of concert-goers fleeing toward the exits.

One concert-goer told The Guardian she heard “quite a loud explosion heard from inside the Manchester arena and it shook, then everyone screamed and tried to get out.”

Nearby Victoria Station, which serves the arena, was evacuated and trains were halted. Around 8:30 p.m. EST, police said they set off a controlled explosion near what they believed to be a suspicious item in Cathedral Gardens, a neighborhood near the stadium. Police determined the suspicious object was in fact abandoned clothing.

The U.S. Department of Homeland Security said it had no information Monday night that would indicate “a specific credible threat involving music venues in the United States.”

“However, the public may experience increased security in and around public places and events as officials take additional precautions,” it said in a statement just before 10 p.m. EST.

The department added it was “closely monitoring the situation” with foreign counterparts to learn more about the reported explosion as well as the injuries and fatalities.

“We stand ready to assist our friends and allies in the U.K. in all ways necessary as they investigate and recover from this incident,” the statement continued. ” Our thoughts and prayers are with those affected by this incident.”

PBS NewsHour will update this story as it develops.

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