Two French girls aged 13 were charged on Wednesday with plotting to kill the entire family of one of the teens, as prosecutors expressed horror at the nature of the plan.
"It's the first time that I and my colleagues have come across a murder plan drawn up by two girls who are so young," said David Charmatz, the prosecutor of Narbonne.
The girls, who lived in a sleepy village near the southern city of Narbonne, were arrested after a knife attack on six-year-old brother of one of them raised suspicion among hospital staff who alerted authorities.
The boy is still in hospital after the March 28 attack, but not in a serious condition. He was stabbed in the neck.
The two girls confessed to planning to kill the boy and one of the teen's parents, and appeared to have no remorse and have not explained their motives, police and prosecutors said.
They have both been charged with attempted murder.
According to reports in France the school were the "middle class" girls attended had become concerned after noticing the girls had shown signs of self-harming. They have both been placed in the care of the state far from their families, France Info reported.