They were rushed to the hospital where their condition was said to be stable.
According to police, Babybai Vishwakarma, Sanjay Vishwakarma and Sunil Vishwakarma, who hail from Hinotia village under Nazirabad police station limits in Bhopal district, had come to the police headquarters to complain about disappearance of Ramcharan, a family member.
According to them, local police were not probing the case seriously.
As a person accompanying them went inside to meet an official, Babybai, Sanjay and Sunil, who were waiting in the parking lot, suddenly drank insecticide.
Ramcharan had disappeared from the village some days ago following a dispute with the panchayat secretary Jitendra Shrivastava, he said.
DGP Nandan Dube has asked Deputy Inspector General, CID to probe the entire matter, he added.