Police were called to a Warwickshire primary school after two 10-year-old boys poisoned their teacher's coffee with a 'bleach-like liquid'.
Emma Place, 39, a teacher from Clapham Terrace Community Primary School in Leamington Spa, had her back turned when the boys poured the substance into her flask.
The Sun said another pupil warned her of the danger before she had a chance to drink the coffee.
A spokesman for Warwickshire Police told the newspaper that the pupils had not realised the 'seriousness or severity' of what they did.
According to the paper, the boys were part of a group who called themselves 'The Mafia' who had drawn up a hit list containing the names of six teacher targets.
It is believed the two pupils were suspended in the wake of the incident last Tuesday.
One parent said of the poisoning: "It's impossible to say how much malice was behind it - or whether it was simply a playground prank that went too far.
"This is a good, friendly primary school, so no one can understand how this incident has happened.
"It has left the parents who know about it in shock, particularly coming in the same week as the tragedy of the teacher killed in Leeds."
Philip Robbins, Clapham Terrace Community Primary School's chair of governors, told The Sun: "The police are involved and we just want to draw a line under it.
"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. Neither the school nor the teacher are pressing charges.
"The pupils were not arrested as far as I'm aware."
He added: "Nobody knows what the substance was."
A spokesman for Warwickshire Police said: "Police were called to Clapham Terrace Community Primary School following a concern for a person's safety.
"Officers provided advice and guidance to pupils and teaching staff. It was determined it was an isolated incident and was dealt with internally by the school.
"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."
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