By Eliza Mackintosh

CNN

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.

• At least 59 people were injured. Police said that victims were being taken to eight area hospitals for treatment.

• British Prime Minister Theresa May, who chaired an emergency Cabinet meeting Tuesday, said authorities believe they know the identity of the attacker.

• Police said they believe the attack was carried out by a lone male attacker, who died in the powerful blast.

• 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.

• Witnesses described a chaotic scene of teenagers crying, while parents desperately tired to search for their children. Some families are still waiting for word from their loved ones this morning.

What we don't know

• The identity of the attacker: May said authorities believe they know who he is, but that his name name can't be released at this point in the investigation.

• The motive: While police say they believe the attacker was working alone, police said they were investigating whether the attacker was part of a larger network or plot. No one has claimed responsibility for the explosion at the time of writing.