Sub-Divisional Police Officer R Srihari said that it was a petty family quarrel which led to the incident.
A housewife, Ramanamma (23), who was depressed after the family quarrel swallowed pesticide at her residence along with two of her children Pujitha (4) and Hema (2), the police official said.
The victims were shifter to Government Hospital Cumbam, where doctors declared them dead, the police official said.
The Ardhaveedu police is probing the incident, the police official said.