Twenty-two people have been killed and 59 injured in a suicide attack at Manchester Arena at the end of Ariana Grande’s concert.
The explosion happened in the foyer at 22:35 local time on May 22.
According to police, the lone male attacker, who died in the blast, detonated an improvised explosive device.
Relatives are using social media to hunt for missing loved ones, and an emergency number, 0161 856 9400, has been set up.
Sixty ambulances attended the incident and those wounded are now being treated at six hospitals around the city.
Eyewitnesses described seeing metal nuts and bolts among the debris, and spoke about the fear and confusion that gripped the concert-goers.
Police have established a help centre at the Etihad Stadium, access Gate 11, for anyone who needs assistance in tracing loved ones.
Twitter has been flooded with appeals from relatives and friends of missing concertgoers via the hashtag #MissingInManchester.
Facebook also activated a safety check feature so that people can let their family and friends know they are safe.
The blast happened close to the entrance to Victoria railway and tram station. The station has been closed and all trains canceled.
Police also carried out a precautionary controlled explosion in the Cathedral Garden area of the city at about 01:32 AM. The force later confirmed it was not a dangerous item.
The Manchester Arena or MEN is the city’s largest indoor venue with a concert capacity of around 21,000.