Windows blew out and ceilings crashed down at Chetham’s School of Music. Upheaval will continue until after the summer holidays while repairs to the medieval buildings are carried out. The main hall, dining room and classrooms of the school, which has nurtured some of the country’s finest musicians, have been wrecked.

Only A-level pupils and those taking other major exams were in school this week. Day pupils were being ferried to the school, inside the police exclusion zone, by a minibus, which also brought food for the boarders.

Canon Peter Hullah, the headteacher of the school, is seeking alternative rehearsal space to prepare for the pupils’ July concert. He is hoping the school is insured against the damage, but he says the work presents a major task.

The blast struck as the school, largely Government-funded, was hosting an open day for new parents.

“We were told to evacuate and stand in the yard,” said Canon Hullah. “Few people were hurt, but one boy’s leg was badly cut and a small group ended up with splinters of glass in their eyes.”

Elsewhere in the city, schools faced disruption this week as staff and pupils struggled to make it through the chaos. Many children were horrified by the blast and afraid of going into town. “I feel nervous and scared - everyone is worried it is going to happen again,” said Miriam Ainsworth, 15, a pupil at Trinity high school.