The incident took place yesterday at Dongariguda village under Kosagumuda Block of the backward district, Nabarangpur Superintendent of Police, Jugal Kishore said.
According to preliminary investigation, the woman Kumari Harijan (29) first gave poison to her three children -- daughters Parvati (7) and Reena (4) and one-and-a-half-year-old son Nilu -- and then consumed it herself after setting her belongings in the house afire, the SP said.
The incident came to light when the villagers found smoke emanating from the thatched house yesterday afternoon and rushed to the spot, police said.
The doctor declared the three children dead and after some time Kumari also died.
Dhaniram Harijan, husband of Kumari was not present as he works as a daily labourer at Nagarnal in Bastar District of Chhattisgarh.
Police are probing all aspects but said at the outset "financial problems" seemed to have played a role in the death.