Twenty-two people, including an eight-year-old girl, have been killed and 59 were injured in a suicide bombing at Manchester Arena, at the end of a concert by US singer Ariana Grande.
A man set off a homemade bomb in the foyer at 22:33 BST on Monday, in what Theresa May called a “sickening” act.
Armed police have arrested a 23-year-old man in Chorlton, south Manchester, in connection with the attack.
Saffie Rose Roussos was a pupil at Tarleton Primary School, in Lancashire.
Her head teacher, Chris Upton, said she had been “simply a beautiful little girl in every aspect of the word” and was “loved by everyone”.
Student Georgina Callander, believed to have been 18, has also been named as among the dead.
She had been studying health and social care at Runshaw College in Leyland, Lancashire.
Sixty ambulances went to Manchester Arena after the attack and the wounded are being treated at eight hospitals around the city. Among them are 12 children under the age of 16.