Twenty-two people were killed and dozens more were injured after an explosion rocked Manchester Arena in the U.K. on Monday night just as Ariana Grande was finishing a concert there.
The suspected bomber was among the dead, according to police.
The attendees — including many children, teens and young adults, and their accompanying parents — were sent scrambling in the blast, and eyewitnesses described to PEOPLE a scene of chaos and fear.
As authorities confirm all of the details of the apparent terror attack, here are five things to know about what happened.
1. Suspected Attacker Is Lone Male: Police
Greater Manchester Police Chief Constable Ian Hopkins said early Tuesday that the explosion occurred around 10:33 p.m. local time Monday near the ticket office outside the arena. The attack was carried out by one suspect carrying a bomb, he said.
Manchester is about a two-hour-and-15-minute train ride northwest of London.
“The attacker, I can confirm, died at the arena,” Chief Hopkins said. “We believe the attacker was carrying an improvised explosive device, which he detonated, causing this atrocity.”
He added, “We have been treating this as a terrorist incident and we believe, at this stage, the attack last night was conducted by one man. The priority is to establish whether he was acting alone or as part of a network.”
The exact location of the explosion had been somewhat in dispute until Manchester police confirmed it was outside the arena. British Transport Police said in the immediate aftermath that it was reported in the “foyer area,” and multiple witnesses described it as being somewhere in or near the front area of the venue.
In a brief initial statement, Manchester Arena (whose representatives could not be reached for comment) said the explosion occurred “outside the venue in a public space.”
In a statement Tuesday, the arena said, “Our community suffered a senseless tragedy. Our entire team’s thoughts and focus are now on supporting the people affected and their families.”
A motive in the attack remained unclear Tuesday, but according to the SITE Intel Group, ISIS has claimed responsibility.
2. Children Are Among the 22 Killed
Local authorities have not yet confirmed the identities of many of the people who died in the explosion, but a few of the victims have been named, including 8-year-old Saffie Rose Roussos, 18-year-old Georgina Callander and 26-year-old John Atkinson.
“The thought that anyone could go out to a concert and not come home is heartbreaking,” the headteacher at Saffie’s school said in a statement.
“Georgina was a lovely young student who was very popular with her peers and the staff and always made the most of the opportunities she had at the school,” said a school she had recently attended.
One of Atkinson’s friends, Tracey Crolla, called him “an amazing young man” who was “so kind and thoughtful.”
Numerous media reports have highlighted Grande’s youth-skewing appeal as an entertainer, and many of the Monday night attendees were children or young adults.
Fifty-nine people were hospitalized after the attack and approximately another 60 “walking wounded” were treated but not hospitalized, according to officials with the North West Ambulance Service.
Meanwhile, multiple desperate parents took to social media in search of their missing kids.
“It’s the most horrible feeling ever to know that your daughter’s there,” one mom, who was still searching for her child, told CNN through tears. “You can’t find her. You don’t know if she’s dead or alive, and I don’t know how people can do this to innocent children.”
Several of the injured were hospitalized in serious condition, according to authorities.
3. British Royals and Other World Leaders React
“The whole nation has been shocked by the death and injury in Manchester last night of so many people, adults and children, who had just been enjoying a concert,” Queen Elizabeth said in a statement issued by Buckingham Palace on Tuesday.
“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.”
In his own statement, Prince Charles said, “That such a large number of people, including so many young concert-goers, lost their lives or have suffered so much in this appalling atrocity is deeply distressing and fills us with intense sadness.”
And the U.K.’s prime minister, Theresa May, called Monday’s violence “an appalling terrorist attack.”
“The cowardice of the attacker met the bravery of the emergency services and the people of Manchester,” she said.
Speaking from Israel, during an international trip, President Donald Trump said, ““We stand in absolute solidarity with the people of the United Kingdom. So many young, beautiful, innocent people living and enjoying their lives, murdered by evil losers in life. I won’t call them ‘monsters’ because they would like that term.”
4. Ariana Grande ‘Broken’ by the Attack: ‘I Am So So Sorry’
Grande took to social media late Monday to share her devastation in the wake of the explosion. Witnesses said she had just finished her last song of the night before the explosive went off.
“Broken. From the bottom of my heart, I am so so sorry,” Grande, 23, wrote on Twitter. “I don’t have words.”
Many others from the music world and Hollywood celebrities expressed their condolences as well. And late-night host James Corden shared a taped video message, reacting to news of the attack.
“I’m telling you, a more tight-knit group of people you will be hard pressed to find,” Corden, who was born in London, said of Manchester. “Strong, proud, caring people with community at its core. The spirit of Manchester will grow even stronger this evening. We’ll all go to bed holding out little ones even tighter this evening.”
5. Local Residents Rally for Hope
Amidst the swirl of bloodshed and confusion, as authorities tended to the dead and wounded and families searched for loved ones, the residents of Manchester began offering their support to those in need.
People living near Manchester Arena used the hashtag #roomformanchester on social media to provide survivors a place to stay overnight. Others nearby were also offering rides to those struggling to get home, and taxi drivers also reportedly gave free lifts to concertgoers.
A branch of the Holiday Inn hotel located near the venue took in around 60 children separated from their parents and others in need of shelter.
Want to help? Here are a few ways to contribute to relief and support efforts.
• RYAN KILPATRICK contributed to this story