A 14-year-old schoolboy has been jailed after he barricaded his teacher inside a classroom then laughed as he sexually assaulted her.
Desperate colleagues tried to break down the door when they heard the teacher screaming for help but could not stop the boy, now 15, from Wrexham.
Staff fought their way into the school's computer room and pulled the 'distressed and terrified' teacher to safety.
The teenager, who admitted intimate assault and was sentenced to four years’ youth detention, had put his hand up her skirt and forced himself on her.
Prosecutor Karl Scholz told Mold Crown Court: 'The teacher and the boy were in the classroom when he closed the door and snapped the latch shut.
'He told her he had things on his mind and took hold of her and hugged her.
'She managed to get away and wanted to leave the room but realised the door was locked.
'The schoolboy then put his hand up the teacher’s skirt and carried out a serious intimate assault on her.'
Mr Scholz said staff outside could hear their colleague scream and the boy laughing.
When they eventually got in the teacher was 'very distressed' and had a 'terrified' expression on her face.
Mold Crown Court court was told the teacher had been unable to return to work since the horrific school sex attack at the 700-pupil high school in North Wales.
The schoolboy, who cannot be named for legal reasons, had previous convictions for two intimate assaults and was on bail for a third when he attacked his teacher.
Steven Edwards, defending, said the boy had suffered a difficult childhood and had been the victim of abuse.
Judge Greg Bull QC told the schoolboy: 'You attacked one of your teachers, barricaded her into the computer room and forced yourself on her.
'It was a terrifying experience for a woman who was only there to try and help you.'
The teenager was also placed on the sex offenders’ register for life.