A 15-year-girl, who has been suspected to be fighting depression since some time, allegedly shot dead her mother and elder brother.

The incident took place in Lucknow on Saturday and the police have taken the teenager into their custody.

A student of Class X, police have informed that the teenager was a trained shooter and she was fighting depression for the past few months.

"The teenager, who is clearly in a state of depression, even tried to harm herself by slitting her wrists open after she killed her mother and brother," the police said.

The father, who is a senior government official, was posted in New Delhi when the incident took place.

"The girl requires immediate medical assistance and proper counselling as well," the police said.

"She hot three bullets- one hit the mirror and the other two killed her mother and her brother," the police said.

"She even wrote 'I am a disqualified human' on the washroom mirror with fruit jam, which made her a suspect," the police said.

ALSO READ | Depression: Nemesis That Needs To Be Defeated

Later, upon being questioned, she admitted to the crime and the police also recovered the murder weapon.

The police, during their course of the investigation, has come up with a lot of revelation about the incident and also about the girl.

"The girl was inspired by Japanese author Osamu Dazai, who talks about the estrangement of the individual from society," the police said.

"A character in Dazai's novel called Oba Yozo tries to adapt, cope and fit in but fails to become a human. The girl identified with that," the police said.

"In her notebook, she has scribbled 'to fail to be human, to be disqualified as a human being'. This is an excerpt from the book 'Longer Human' by Dazai," the police added.

"Depression has been one of the least talked about topics in any Indian household. We don't know what was the reason for her such depressive nature," the police said.

"We will try to find out the cause with the help our medical experts," the police added.

"Teenage depression is triggered by a number of factors and we will need to work hard and find out what triggered hers," said a medical expert examining the girl.

"It is too early to comment now," she added.