A teacher narrowly escaped being poisoned when two 10-year-olds put a “bleach-like liquid” in her coffee.
Police were called to the school in Warwickshire on Tuesday, just a day after Ann Maguire was stabbed to death in a classroom in Leeds.
Emma Place, a teacher from Clapham Terrace Community Primary School in Leamington Spa, reportedly had her back turned when the boys poured the substance into her flask.
Another pupil warned her of the danger before she had a chance to drink the coffee, The Sun said.
A spokesman for Warwickshire Police told the newspaper the boys had not realised the seriousness of what they were doing.
The age of criminal responsibility is 10 in the UK, meaning they could have been arrested and charged with an offence.
Philip Robbins, chairman of the school’s governors, said officers spoke to the children but the school and Ms Place were not pressing charges.
He told the newspaper: “Emma dealt with it well. Of course the school is giving her support.
"The school has dealt with the situation appropriately and we're hoping to move on.
"It was put in the hands of the police."
He added that "nobody knows what the substance was".
A spokesman for Warwickshire Police said advice and guidance was given to teachers and pupils at the school.
He told The Sun: ”The evidence was taken away by police but we were guided by the school that it was an isolated incident that got out of hand.
“I don't think the pupils realised the seriousness or severity of the situation.”
A letter about the incident was sent home to some parents at the school, which had recently been given a “good” Ofsted rating.
Additional reporting by PA