A teenager has admitted attempting to wound a teacher in a knife attack that led to three Gloucestershire schools being locked down, carried out after he told friends he wanted to kill somebody and researched how to buy firearms in the UK. The 15-year-old boy pleaded guilty to trying to unlawfully and maliciously wound Jamie Sansom, a maths teacher, in a school corridor with intent to do him grievous bodily harm. The teenager, who cannot be identified for legal reasons, had previously admitted possessing a knife in the attack on 10 July at Tewkesbury academy. At a brief hearing at Bristol youth court, the boy spoke only to confirm his address and age. He had an intermediary beside him in the dock to help him understand proceedings and his parents sat in front of him in the body of the courtroom. The facts of the case were not given. Remanding the teenager into a youth detention facility, the district judge, Lynne Matthews, told him: “You will be remanded until 28 September, which means I’m not sending you home.” During preliminary hearings in Gloucestershire, which can only now be reported, it was claimed the boy had said he wanted to kill somebody, rob a bank and “live a life of crime” and had searched how to buy firearms. Sadie Waits, prosecuting, said that at 9.03am on 10 July police had received a call from a male whispering to the call handler that someone was going to stab a teacher at Tewkesbury academy. A few minutes later, wearing a snood over his face and a hat, the teenager knocked on the door of a classroom where Sansom was working with pupils. Sansom opened it and the boy told him: “Come here.” “As Mr Sansom approached [the boy], he saw that he was holding a knife in his right hand. It was described as being similar to a vegetable peeler with a light blue handle and was 6in [15cm] in length, including the handle,” said Waits. “[He] then said to the teacher: ‘I’m sorry’ as he reached out slowly pointing the knife towards the teacher’s stomach. Mr Sansom describes the feeling as if a needle had been poked into his stomach and shouted at the youth: ‘What are you doing?’” Sansom told colleagues he had been stabbed and was taken to an office where an ambulance was called. The boy fled the scene, discarding a backpack he had with him, as well as the snood and hat. News of what had happened spread quickly through the community. The teenager’s mother contacted him and asked him to give himself up. He apologised to her and said: “Goodbye forever … But remember I always loved you guys.” He added: “Tell everybody I love them.” The phone number used was the same number that called the police at 9.03am. At about 11am a local primary school reported that someone was trying to get through its gates and a short time later the police located the boy about five miles (8km) from the academy. Firearms officers attended the scene and challenged the boy, who dropped the knife, and he was arrested. The court was told Sansom was taken to Gloucestershire Royal hospital by ambulance and was treated for a 1cm stab wound above his belly button. A CT scan was conducted and there was no injury to any organs. Waits said the phone call made to the police before the attack showed it was premeditated. Sansom, who has taught maths at the school since 2017, was discharged from hospital on the same day he was attacked and has said he is “recovering well”.