UK Critical threat level explained

The UK threat level has just been raised to Critical, the highest possible level out of five. This is the first time the level has been raised to Critical since 2007.

According to the MI5 website this is what the various levels mean:

LOW means an attack is unlikely.

MODERATE means an attack is possible, but not likely

SUBSTANTIAL means an attack is a strong possibility

SEVERE means an attack is highly likely

CRITICAL means an attack is expected imminently

Following the events outside Manchester Arena last night here is a recap of what we know so far.

• The attacker is thought to be 22-year-old Manchester-born Salman Abedi.

• Prime Minister Theresa May made statement in Downing Street confirming the details.
• Theresa May called it a "Callous attack carried out with cold calculation".
• Queen condemns "act of barbarity" that has "shocked nation", the full statement can be read below.
• 'Bomb' went off at 10.33pm on Monday evening.
• 22 killed.
• 59 injured.
• Victims treated at eight hospitals across Greater Manchester.
• Greater Manchester Police (GMP) release a freephone number for people concerned about loved ones 0800 096 0095.
• A vigil will be held at 6pm tonight in Albert Square, Manchester.
• Manchester Victoria train station remains closed.
• First victim confirmed as 18-year-old Georgina Callander from Lancashire.
• Police have arrested a 23-year-old man in South Manchester thought to be in relation to last night's incident.
• IS says it carried out the terror attack.

Police are appealing for anyone with 'dash-cam' footage in Manchester between 8pm and 11pm on Monday night, to send it to them as a 'matter of urgency through this website.

Ariana Grande tweeted last night simply saying, 'broken, from the bottom of my heart, i am so so sorry. i don't have words.' sic

GMP release a full statement on last night's incident.

The Queen made a statement, the full statement can be read below.

Prime Minister Theresa May gave a statement earlier from Downing Street, later today she will be travelling to Manchester.

Here is a recap of how the events unfolded last night.

Celebrities have paid tribute to the victims of the Manchester terror attack.

Listen to an eye witness account from Shauna who had been watching Ariana Grande on Monday evening.

Police has said concerned friends and family should call the freephone number 0800 096 0095.