Ofsted has published a damning report on a school that faced walkouts by staff over safeguarding concerns.
Inspectors, who rated Starbank School, in the Yardley area of Birmingham, "inadequate", said the behaviour of a "significant minority" of pupils was "poor and unsafe," leaving other youngsters, as well as staff, feeling vulnerable.
The report raises concerns about discipline, warning that too many pupils in the secondary part of the all-through school are "defiant," ignore requests and show "a complete lack of respect" for leaders and staff.
About 20 members of the NASUWT teaching union at Starbank School's Hob Moor Road site went on strike earlier in the summer to express their concerns about pupil "indiscipline" and staff safeguarding measures. They also called for a knife audit at the school.
Teacher strike over safeguarding concerns
Inspectors carried out an unannounced visit to the school in July and produced the new report, which says that since a previous inspection, the school's leaders "have not kept pace with managing the expansion of the school's age range and size sufficiently well.
"Worsening behaviour, fractured leadership and staff absence have led to the school's decline," the report states.
It says that "the behaviour of a significant minority of pupils in years 7 to 11 is poor and unsafe".
"Their aggressive, defiant behaviour leaves other pupils and some staff feeling vulnerable."
In a section on behaviour, inspectors concluded: "Too many pupils in the secondary phase show a complete lack of respect for leaders and other school staff.
"All too often, pupils are defiant and ignore reasonable requests from staff to follow instructions.
"In some lessons, pupils shout out and argue with the teacher. In addition, some pupils do not wear the correct school uniform."
It notes that pupils say views and reports about bad behaviour, including the use of knives, are "over-exaggerated" and that inspectors agreed. The report adds that "media myths such as 'Fight Thursday' have only added to the difficulties that leaders are experiencing in managing behaviour".
Primary pupils show good behaviour
The report does note that the primary part of the school is "well led and managed", with pupils achieving and showing good behaviour.
Youngsters in the early years also make good progress because staff give them "good-quality learning experiences and a high level of care".
A Birmingham City Council spokesman said: "We have seen the Ofsted report and, like the school, we are, of course, disappointed with the findings.
"An improvement plan is already in place and we will continue to work closely with the leadership team to address all the issues identified so that all children get the education they need and deserve. The report highlights a number of strengths at the school, such as early years and primary phase teaching, as well as family and community engagement, which serve as a basis on which to achieve sustainable improvement."
Starbank is an all-through school that teaches three- to 16-year-olds and had previously been rated "outstanding" by Ofsted in May 2012.