The victim was sleeping alone at her house at Guthni bazar last night when the culprit entered and committed the crime, Guthni police station sub-inspector Ramadhar Singh said.
The family members had gone out to pay their obeisance to Goddess Durga and on returning found her lying dead on her bed.
Following complaint to the police, raids are being carried out to nab the perpetrator.
Irate locals gheraoed the police station and forced shops to down shutters against the incident, demanding the arrest of the culprit.
BJP MLA Ramayan Manjhi, who represents Darauli assembly seat in Siwan district, sat on dharna with his supporters outside Guthni police station demanding justice for the aggrieved family.
Two days back a three-year-old was raped in Delhi allegedly by her play school owner.