A teenager who attacked two sleeping students and a teacher with hammers at a private school in Devon has been sentenced to life in prison with a minimum term of 12 years after being found guilty of attempted murder. The 17-year-old, who cannot be identified for legal reasons, was armed with three claw hammers and waited for the two boys to be asleep before attacking them at Blundell’s school in Tiverton, Exeter crown court heard. He was wearing just his boxer shorts and used weapons he had collected to prepare for a “zombie apocalypse”, the court was told. The boy, who was 16 at the time of the attacks, admitted assaulting the two boys and the housemaster at the boarding school but claimed he was sleepwalking. The judge, Mrs Justice Cutts, said: “[The victims] did not know what was coming. They could not defend themselves in any way. They were very badly hurt indeed.” She said he had planned the attacks, adding: “You did so because you deliberately intended to kill them. You took a hammer to the scene to use as a weapon.” The judge said the boy experiences an autism spectrum disorder – which he rejects – but she said why he carried out the attack may never be known. She said “both boys may have died” but for the intervention of staff, pupils and medical teams. The judge said the boy was “under stress at the time”, but added: “You knew the difference between right and wrong and you had planned to kill those boys and obtained hammers as weapons.” She said his autism meant he became increasingly isolated living and studying at the school and “retreated into the online world”. Cutts said he posed a high level of danger to the public from further violence and it was unknown if he would ever cease to be a danger. The two pupils were asleep in cabin-style beds in one of the co-ed school’s boarding houses when the defendant climbed up and attacked them shortly before 1am on 9 June last year. The housemaster, Henry Roffe-Silvester, who was asleep in his own quarters, was woken by noises coming from the boarding house and went to investigate. When he entered the bedroom where the attack had happened, he saw a silhouetted figure who then turned towards him and repeatedly struck him over the head with a hammer. Another student heard Roffe-Silvester shouting and swearing as he fled the bedroom and dialled 999, believing there was an intruder. The two boys were discovered in their beds a few minutes later. They had sustained skull fractures as well as rib, spleen and lung injuries and internal bleeding. The court heard both were living with the “long-term consequences” of the attack but had no memory of it. Roffe-Silvester suffered six blows to his head. The defendant maintained he was sleepwalking at the time of the attacks, which would have meant he would not have been guilty of attempted murder. But the jury found him guilty of three counts of attempted murder.