Enraged over an issue of a mobile phone with his sister, a 17-year-old boy allegedly shot himself dead with a country-made pistol on Sunday in Dwarka's Bindapur area, police said.
The deceased was identified as Gulshan, they said.
Police were informed about the incident at 6.18 am by the hospital authorities.
The injured was rushed to a hospital where he was declared brought dead, police said, adding that he had suffered a gunshot wound.
It is suspected that the shot was fired from a very close range, a senior police official said.
Police also found four live cartridges in Gulshan's pocket.
The deceased's father, Ranbir Singh, told the doctor that Gulshan had injured himself.
He told the police that his son arrived in the morning and rang the doorbell. On opening the door, he found his son lying with an injury.
Gulshan was angry with his sister over an issue of mobile phone and smashed her phone before leaving home last night, the officer quoted Mr Singh as having said.
The pistol used to commit the suicide was recovered, police said, adding that it was found loaded with two rounds.
The weapon was picked up by his uncle as he felt the pistol could be mishandled by someone after the incident and he later produced the same before the police, the officer added.
A case was registered, police said, adding that the matter is being investigated.
For more Delhi news, click here