The girls duo, identified as Rani Kumari (5) and Pinki Kumari (3), consumed the snack last evening after purchasing the same from a nearby grocery shop and took ill soon after, Shivajinagar police outpost's Station House Officer (SHO) Madan Prasad said.
They were admitted to a Primary Health Centre (PHC) for treatment where the attending doctors referred them to Darbhanga Medical College and Hospital (DMCH) where they were declared dead on arrival, he said.
An FIR has been lodged against the shopkeeper Arun Kumar, who has been arrested and his shop sealed, Prasad said.
The samples of the spurious snack has been collected for laboratory test for examination, he said.