A 17-year-old boy was shot dead in south Delhi's Neb Sarai area, police said on Monday.
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.