The victims were identified as Anugoju Uma (33) and her two children Kaushik (10) and Vinmaya (8).
Police found a suicide note at the spot, in which Uma said that she decided to end her life due to severe harassment by her in-laws and her husband Shoban Babu.
"Since the door of the victims' house did not open even after 10 am, the neighbours knocked on the door. However, finding it locked from inside, the neighbours broke the window open and found the woman and her children dead," Circle inspector of Subedari Police Station Satish, said.
Police said fed up with the harassment, Uma poisoned her children and consumed it herself. The bodies were later handed over to her family members.
A case has been registered and investigation is on.