London(CNN) An explosion ripped through a crowd of people leaving an Ariana Grande concert in Manchester, England on Monday night. The deadliest attack on British soil since the 2005 London bombings has left a country in mourning and police searching for answers.
Here's what we know -- and don't know -- so far.
What we know
• At least 22 people, including children, were killed in the blast, which rocked Manchester Arena at around 10:35 p.m. local time (5:30 p.m. ET) as fans were leaving the venue.
• Three victims have been named, including an 8-year-old girl, an 18-year-old woman and a 26-year-old man.
• At least 59 people were injured. Police said that victims were taken to eight area hospitals for treatment.
• Police have named 22-year-old Salman Abedi as the suspected bomber. He is believed to have died in the powerful blast but has not yet been identified by the coroner, according to police.
• Abedi was born in the United Kingdom in 1994, according to Prime Minister Theresa May.
• He is of Libyan descent, sources in Manchester's Libyan community told CNN.
• ISIS claimed responsibility for the attack, but offered no evidence to support the claim.
• The UK raised its terrorism threat level to "critical" -- the highest level -- for the first time in a decade on Tuesday.
• Prime Minister May warned that intelligence services believe an attack may be "imminent."
• Police have arrested a 23-year-old man in connection with the attack.
• Police have conducted at least two raids in Manchester as part of the investigation.
Deadly explosion at Ariana Grande concert
People in Manchester, England, gather in St. Ann's Square on Thursday, May 25. They were observing a national minute of silence to remember
the victims of a suicide bombing at an Ariana Grande concert.
A police officer guards a house in Manchester as investigations continued on May 25. Police say a man carrying explosives
acted as a lone attacker and died in the blast.
Flowers and tribute messages are left for victims in St. Ann's Square.
A women sheds tears after observing the minute of silence in St. Ann's Square.
A Manchester road is closed off as police raids continued on May 25.
Local residents hold Manchester City and Manchester United soccer jerseys during the national minute of silence.
Police officers deliver flowers to a makeshift memorial in Manchester on Wednesday, May 24.
Women cry after placing flowers in Manchester on May 24.
A forensics team works at the scene of the explosion on Tuesday, May 23.
British Prime Minister Theresa May condemns the "callous terrorist attack" as she
delivers a statement in London on May 23.
Police help someone after the attack at Manchester Arena on Monday, May 22.
People gather outside the arena. "We can confirm there was an incident as people were leaving the Ariana Grande show last night," police said on Twitter early on Tuesday. "The incident took place outside the venue in a public space. Our thoughts and prayers go out to the victims."
People receive medical attention at a railway station close to the arena. The incident happened shortly after Grande had left the stage, shortly after 10:30 p.m. (5:30 p.m. ET) according to eyewitnesses. Calvin Welsford, an 18-year-old concertgoer, said that he heard a "loud bang" a couple of minutes after Grande's set had finished.
Paramedics respond to the scene.
Emergency workers and concert attendees gather outside the arena.
People stand by a cordoned-off street close to the arena.
Greater Manchester Police tweeted that emergency services were "responding to (a) serious incident at Manchester Arena. Avoid the area. More details will follow as soon as available."
People are escorted away from the arena.
People sit outside near the arena. The crowd was made up of mainly younger people who had come to see Grande in her first of three scheduled concerts in the UK.
An injured man is helped at the scene.
People hug near armed police who responded to the scene.
• An improvised explosive device is believed to have been used in the attack, police said.
• Arena representatives said that the explosion occurred outside the main concert area, in a "public space."
• The arena, built in 1995, has a capacity of about 21,000 people. It is not clear how many concertgoers were inside the venue on Monday evening.
What we don't know
• The motive: While police say they believe Abedi was working alone, they were investigating whether the attacker was part of a larger network or plot. Although ISIS claimed the bombing, the terror group did not mention a name and did not post a photo or provide any additional details.