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.
• 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.