A preliminary inquiry has revealed that the family consumed poison, they said.
According to police, the deceased have been identified as Murugan, hailing from Idukki district of Kerala, his wife and daughter.
The daughter was pursuing her MSc course at a private college in Pollachi, about 30 km from Udumalpet.
Murugan was working in an estate at Marayoor and was missing along with his wife and daughter since last evening, police said.
Passers-by noticed the bodies and informed police.
Investigations are on to ascertain the reason for the family's action, police added.
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