A group of three California elementary school students are facing expulsion for attempting to poison their fifth-grade teacher with rat poison.

The students at Balderas Elementary, ages 10 and 11, put rat poison in their teacher's cup of coffee last December. Before the teacher drank any, the student who put the poison in had a change of heart, knocking over the coffee during class, Fresno Unified School District PIO Susan Bedi told ABC News.

At home that day, that student told his parents that he had saved a teacher's life, leaving out the details, Bedi said.

This month, while waiting for the child at the end of the school day, the student's parent asked an administrator at school if the teacher was doing O.K. From there the story unfolded.

Eventually, all three students admitted involvement, although it still isn't clear why they did it, and the school district took disciplinary action.

"We have a zero-tolerance policy for violence, and the students are currently in the process of suspension, with a recommendation for expulsion," Bedi said. "They will not be returning to that school."

No criminal charges have been filed against the students by the Fresno Police Department, ABC's Fresno affiliate KFSN reports.

There were some reports that a cupcake had also been poisoned and given to the teacher, but Bedi says there is no evidence to support that.

The Fresno Teachers Association released a statement saying they appreciate the swift action by the school district, but that this case is indicative of a larger problem in the city's schools.

"This is but the latest example of the dangerous conditions that exist in Fresno Unified due to inconsistent enforcement of discipline and lack of consequences for students daily," FTA President Greg Gadams said. "Something has to be done and this is a prime place to start insuring teacher safety and student accountability."