According to the sources, the woman was upset over the disabilities of the children.
Husband of the woman works in Shimla while she was living with the minor children in Jharrajputan village of the district, police said.
Last night, she allegedly fed Sulphas tablets to the two children and later consumed it herself, police said.
After consuming the poisonous tablet she called up her husband to inform about it, police said.
The youngest child, a girl, died on the spot while the woman and the son succumbed in a hospital later, police said.