Sandeep, a Class IX student, was killed in Pandav Nagar area of East Delhi, according to police.
All the three attackers are juveniles and have been taken into custody. Two of them are students of Class XII while one of them is in Class X.
They all lived in the same colony, police said.
"One of the three boys demanded money from Sandeep to purchase cigarettes. Sandeep, however, informed his mother about the harassment," said a senior police official.
Sandeep was taken to a nearby hospital where he was declared dead. According to doctors, the boy died of internal injuries.