Aged nine, 13 and 18, the victims were found together in a field with head and neck injuries.
They failed to return home after going out to nearby fields to collect fodder – leaves and plants that are fed to cattle – on Friday.
Police say the girls were found dumped in a field with head and neck injuries
Families of the girls told local news they suspected they had been gang raped and murdered.
Locals carried out searches overnight before the grim discovery was made the following day.
All three come from the same village, Katiyari, in Uttar Pradesh’s Deoria disctrict, in the east of the country regarded by many as the rape capital of the world.
Police in the region say they are awaiting the results of post mortems before deciding whether to launch a rape and murder investigation.
“The bodies bear head injury which seems to have caused the death. The case has been filed and we will look whether there was any sexual offence,” said Manoj Kumar, Superintendent of Police, Deoria.
India has a long history of problems with gang rape. The most notorious case in recent years occurred in 2012 when a 23-year-old physiotherapy intern was brutally raped and murdered as she travelled on a private bus in Delhi.
The incident sparked protests in the country and calls for a change in attitude towards the treatment of women.