Two 15-year-old boys have been convicted of plotting to murder fellow students and teachers at their school.

The teenagers, who were said by prosecutors to have “hero-worshipped” the perpetrators of the 1999 Columbine massacre, were found guilty of conspiracy to murder after planning an attack on their school in Northallerton, North Yorkshire.

The boys, who were 14 at the time of the offence, sat motionless alongside their tearful mothers as the verdicts were read out at Leeds Crown Court on Thursday.

During the three-week trial, jurors heard how the boys had prepared a “hit list” of people they wanted to kill, including fellow students and teachers who had supposedly bullied or wronged them.

Analysis of their devices showed that they had researched weapons online and had both downloaded a bomb-making manual.

The older defendant, described as the “leader” of the pair, had supposedly “idolised” Eric Harris, who took up arms with fellow teenager Dylan Klebold and carried out a massacre at Columbine High School, Colorado, killing themselves and 13 others.

The same boy was later found to have kept a diary in which he espoused what prosecutors described as a “far-right wing ideology” and discussed his motivations for wanting to carry out an attack.

The pair were questioned by police officers when, in September 2017, the younger boy told a schoolgirl via Snapchat that they were planning to carry out a shooting.

When she asked if he was joking, he responded: “No. No one innocent will die. We promise.”

The next day, he made what the prosecution described as “clear and unvarnished” confessions, firstly to a teacher, and then to police officers.

During his evidence, the teacher told the court that the boy had said that his targets were “infecting the gene pool” and that he and his friend were performing a “service to society”.

The older boy’s girlfriend claimed that, shortly after that incident, he spoke of a plan to murder her parents and run away together, so that he could become a “natural born killer”.

The schoolgirl, who started dating the boy in June 2017, claimed he described her as “his Dylan Klebold” and encouraged her to give him access to her father’s shotguns.

The teenager, described as “devious” and “primitive” by the girl’s mother, was cleared of one count of aggravated burglary.

He was convicted of unlawful wounding, after carving his name into his then-girlfriend’s lower back.

Officers searched the boy’s “hideout”, where they discovered a rucksack filled with screws, boards, and a flammable liquid which, prosecutors suggested were instruments with which to build an explosive device.

The pair will be sentenced at Leeds Crown Court at a later date.

Counter Terrorism Policing North East (North East CTU) claimed that both the boys had a “very real interest in violence”.

In a statement, Detective Superintendent Martin Snowden, the head of the North East CTU, said they were “very grateful” to North Yorkshire Police for their assistance during the investigation.

“There is no understating the severity of these offences and the potential implications had their plans not come to the attention of the authorities,” Mr Snowden said.

He added: “These boys demonstrated a very real interest in violence and had both expressed a desire to act out their fascinations.

“Disturbingly, they had gone beyond the fantasy and had begun to take very real steps towards making it a reality.”

Superintendent Allan Harder, head of safeguarding at North Yorkshire Police, said: “We want to reassure the school community and the wider public that the health and well-being of young people and their families will remain at the top of our agenda.”