Pinki alias Sakhi, a student of Class 12, was attacked in Buddh Vihar in Munirka area, a police official told IANS.
Police said an unknown person barged into the victim's house, shot her in the chest and fled.
The victim was a student of government school in RK Puram Sector 5.
"Her aunt was present in the house when the incident took place. After shooting her, the boy whose identity is yet to be ascertained, fled from the scene," the official said.
Pinki was rushed to Safdarjung Hospital where she was declared brought dead.