Police said the tragic events appear to be the fallout of a love affair gone awry.
A Madhya Pradesh policeman entered a woman's home and opened fire, killing her father and injuring her and her brother, and then died by suicide by jumping before a speeding train.
The condition of the 25-year-old woman and her brother is critical, police have said.
Subhash Kharadi (26), who worked as a police driver in Dewas, entered the home of Jakir Khan (55) in Shajapur district late on Sunday night, police said. He was armed with a countrymade pistol.
He opened fire at the woman Shivani, her father Jakir Sheikh and her brother before fleeing the spot.
Kharadi then put up a Facebook post with pictures of him and the woman, with the caption, "I killed her because she betrayed me. I have given her a pain that she will never forget." Hours later, his mutilated body was found on railway tracks.
According to police, the tragic series of events appears to be the fallout of a love affair gone awry.
The woman was first rushed to a nearby hospital and then shifted to Indore for better treatment. Visuals from the hospital showed her bloodied clothes as she was carried into an ambulance to be shifted to Indore.
District police chief Yashpal Singh Rajput said their investigation is on. Sattar Khan, former sarpanch of the area, said police should ensure speedy probe and justice in the shocking case.