The deceased were identified as Partho Pal, 10, and Prattay Pal, 5, sons of Parimal Pal of the village.
Mintu Rahman, officer-in-charge of Chapainawabganj Sadar Police Station, said Partho came in contact with a live electric wire from a table fan around 11am.
Later, his younger brother Prattay and mother Riva Rani also got electrocuted while trying to save Partho.
After noticing the incident, locals took them to the sadar hospital where doctors declared the siblings dead.
Also read: Man, nephew die of electrocution in Kishoreganj