A 13-year-old boy who went in to a south Lincolnshire school with an air weapon and an axe will be sentenced later this month.
The youth had to be dealt with by staff after firing one pellet from the air weapon in to the ground, a court heard.
He was also armed with a screwdriver and an axe which he had tucked in to the webbing of a camoflage vest, and was wearing a t-shirt baring the words 'Natural Selection.'
A youth court heard the boy had spoken to other pupils and had made comments about having a plan, a zero day and shooting up the school.
The court heard how the youth took a bus to school with the air rifle hidden in a guitar case and then got changed in the toilets where he had also stored a can of hairspray and 20 bonfire type sparklers.
The boy, who can not be named because of his age, pleaded guilty to possessing a firearm with intent to cause fear of unlawful violence to another person and having an axe on school premises when he appeared at Lincoln Youth Court on Friday.
At a previous hearing prosecutor Jim Clare described the events as "chilling" and asked for the boy to be remanded in to custody despite his young age.
"These are quite chilling events, he is only 13 and was a pupil", Mr Clare told court.
"At 9.12am police attended the school after he was detained by staff.
"He was in possession of an air rifle, an axe and a screwdriver. The words 'Natural Selection' were written on his t-shirt and he was also wearing a camoflage vest.
"He had left behind other items in his locker and in the toilet, a can of hairspray and 20 bonfire type sparklers.
"He had taken the bus to school with the air rifle in a guitar case."
Mr Clare described how events unfolded after a female member of staff spotted the boy near the toilets with the air rifle slung over his shoulder.
"She confronted him and he walked away. She followed him, he went outside and was stood on a grassy area," Mr Clare said
The woman went to get another male member of staff who told the boy to 'put it down.'
They were then joined by a senior female member of staff who recognized the boy as a pupil.
"He was told very firmly 'to put it down.' He also had an axe in his webbing," Mr Clare added.
"He fired a pellet in to the ground and then put it down."
The boy was asked to write a statement to explain his actions in the wait for the police to arrive and his friends were also spoken to.
Mr Clare said the boy claimed he wanted to "send a message to stop the bullying."
Other pupils said that he spoke about the Columbine school massacre in America and made comments about having a plan, a zero day and shooting up the school.
Mr Clare told the court: "There were 20 to 40 pellets with the air gun. There was a search at his house where a number of items were seized.
"An A4 exercise notepad set out things he planned to do, a zero day.
"There was also a hit list of people, his intention it would seem of causing them some harm.
"There were references to the Columbine shooting, the Nazis and Natural Selection which was on his t-shirt."
Mr Clare added: "These are a chilling set of circumstances, we have the hit list of other vulnerable youngsters."
The boy, who has been remanded in to secure local authority care, stood in the dock wearing a navy blue tracksuit as he admitted both charges which occurred on 13 November last year.
He was supported by his mother and step father who sat in front of the dock.
Roger Lowther, mitigating, said while the boy had no previous convictions there was no application for bail.
District Judge Peter Veits adjourned the case for a youth offending report on the boy. He will be sentenced on 26 January.
Remanding him back in to secure care the Judge said: "Obviously I am concerned about what happened and what you wrote in the notebook."