Three class 11 students of Kendriya Vidyalaya, Baran died by consuming a poisonous substance after they entered a suicide pact on Tuesday.
"Prima facie it seems the girls were under pressure from parents and teachers to perform well in studies. They had failed two class tests recently. We also learnt that the parents had pressurised the girls to opt for biology stream," said KB Vandana, superintendent of police, Baran.
According to the police, after tuition on Monday the trio stopped at the house of one of the girls. Shortly after, they left for the nearby market after which all of them left for their respective homes.
They started vomiting as soon as they reached their homes and were rushed to a government hospital by their parents. But they could not be saved, the police said.
Doctors said all the girls were in critical condition when they were brought to Radha Krishnan Hospital.
"The girls died due to consumption of aluminium phosphide, commonly known as sulphas," said Dr Kamlesh Aggarwal from the hospital.
Police claim to have recovered a suicide note from one of the girls saying they were taking the extreme step on their own, and no one was responsible for it. But the parents have alleged foul play.
The police have taken the biology teacher and chemistry teacher into custody after parents lodged a complaint of mental harassment against them.
Principal of the school Archana, who goes by one name, told HT, "The teachers have to produce results, so they encourage students to work hard.
If a student takes stress and ends life it is not the fault of the teacher. There has never been physical or mental torture from the teachers' side."