Prince Bishop School in Middlesbrough in special measures
Pupils with special educational needs were let down when a school was put into special measures, a council has admitted.
Ofsted inspectors said behaviour, safety, leadership and teaching were inadequate at Prince Bishop School in Middlesbrough.
The head teacher and two staff have been suspended.
Richenda Broad, Middlesbrough's director of learning, said: "We've done a huge amount..to change the ethos."
Ofsted carried out the inspection in September and published the report on Tuesday.
Asked if she felt the council had let children at the secondary school down, Ms Broad said: "I think it would be hard to go away from that judgement. Of course they've been let down."