An 11-year-old boy was charged on Thursday with attempted murder after stabbing and seriously injuring a classmate in the central city of Lyon, a source close to the case said.
The child, who cannot be named for legal reasons, "admitted the facts" in court, the source told AFP on condition of anonymity.
The incident took place on Wednesday at the Anatole-France primary school in a poor, high crime area of the city.
The 11-year-old stabbed a 12-year-old in the stomach in front of their classmates, said a police source, adding that the victim had allegedly tried to extort money from him.
The child was temporarily placed with a foster family after being charged.
Under French law children between the ages of 10 and 13 can be held criminally responsible, but will not be imprisoned.
Instead they can be punished with a warning, be made subject to house arrest or forced to undergo compulsory civic training.
"These two students were not known for being violent. They dealt with matters among themselves and the only response was violence. That means the community failed and that makes me angry," said communist local mayor Michele Picard.