An elderly woman Draupdi Devi and her two grandchildren started vomiting after eating rice and vegetable yesterday, Officer-in-charge of Sanokhar police station, Kaushal Kumar, said.
The three were admitted to a local government hospital where the two children died, while the woman succumbed during treatment at Jawaharlal Nehru Medical College in Bhagalpur, he said.
Daughter of the deceased woman alleged that her sister-in-law had laced the food with poison resulting in three deaths, including her two children.
On the basis of the complaint, police have arrested her sister-in-law, the officer added.