Six persons, including the teenager, have been killed in leopard attacks in the district since November.
According to reports, the villagers cordoned off a sugarcane field and began combing the field when they saw the big cat crouching in a corner. They shot the leopard and dragged its carcass up to the village.
Senior officials, including district magistrate Ramakant Pandey, Najibabad SDM Sangita and SP (city) Laxmi Nivas Mishra reached the village with a large number of policemen.
The boy's body has been sent to the district hospital for autopsy and a post-mortem was also carried out on the leopard.
The leopard was an adult male, about seven years old.
Najibabad divisional forest officer Manoj Kumar Shukla said, "The leopard killed Prashant Kumar, 14, of Bhogpur village. Later, villagers shot the big cat dead. The boy's family will be given Rs 5 lakh as compensation."
SP (city) Mishra said that a case will be registered in this connection based on the complaint of forest authorities.
According to officials, Prashant Kumar, son of Jai Prakash, was a class 7 student at the government primary school. He had left school after taking his midday meal. The school is located on the outskirts of Bhogpur village, near sugarcane fields.
He was walking towards the sugarcane field when a male leopard suddenly emerged from the cane stalks, pounced on him, dragged him into the field and killed him.
A passerby, who witnessed the attack and tried to rescue the boy, was also injured.
As news of the boy's death spread in the village, hundreds of villagers, including the deceased's family, picked up their guns and went to the cane field where the killer leopard was said to be hiding.
Meanwhile, the Basic Shiksha Adhikari (BSA) Mahesh Chandra has set up an inquiry and sought an explanation from school staff of Bhogpur as to why the student was out during the school time.
The BSA said all teachers had already been instructed not to allow any student to play on its ground or go near the cane fields alone.
( With inputs from IANS )