The incident took place on Sunday night when the victim Sahil and his friends were sitting on the terrace of a stitching centre in Tigri, they said.
The victim received a call and went out to attend it. He was in no time surrounded by a group of persons, one of whom shot him in his stomach and thigh, police said.
Sahil was rushed to a hospital where he died during treatment, they said.
A man, presumed to be a juvenile, has been detained, police said, adding that his age was being verified.
It is suspected that the killing was a fallout of a quarrel between Sahil's friend and his neighbour. Sahil had intervened in the matter and had threatened to teach the other party a lesson which enraged them and they decided to exact revenge, police added.