Three persons were critically injured when a bomb exploded at Katma village in Bihar's Madhubani district on Tuesday, a day before the fourth phase of Lok Sabha polling in the state.
Shanti Devi was injured after the crude bomb, which she found lying on the ground, exploded in her hand.
Her husband and a neighbour's son, who were standing nearby, were also wounded in the explosion.
All of them have been admitted to a hospital.
Seven constituencies are going to polls on Wednesday in the fourth of the six-phase Lok Sabha elections in Bihar to decide the fate of 94 candidates.
All the seats are in the Kosi river belt - Madhubani, Jhanjharpur, Madhepura, Darbhanga, Samastipur (SC Reserved), Begusarai and Khagaria.