Sanjay was attacked in Pul Prahladpur while he was returning home from school in the afternoon. One the attackers was his classmate, police said.
He was stabbed thrice on the chest and thigh and he died on way to the hospital.
Police are yet to arrest the attackers.
Police suspect that Sanjay was attacked since he had slapped his classmate for teasing his sister.
The boy studied in Class 11 in a government school.