Armed Maoists burnt four trucks near Amas police station in Gaya and also blasted the block office at Banke Bazar.

Thakur said the Maoists unleashed violence to enforce their shutdown to protest Obama's visit to India Nov 6-9. Maoists began their shutdown across India Sunday night.

The violence worried top police officials in the state as it happened a day ahead of polls in 35 constituencies in drought-hit districts Tuesday.

Though campaigning ended peacefully with no major incidents of violence reported, ensuring safe polling in this phase will be a challenging task for the Election Commission as well as the state government as almost a third of the constituencies are in Maoist-affected areas.

Till now, the four phases of state elections - to pick a new 243-member legislative assembly - have passed off peacefully except for stray incidents of violence.

The outlawed Communist Party of India-Maoist (CPI-M) early this month declared that it would intensify attacks to disrupt the election process and to enforce its boycott of the polls. As many as 33 of Bihar's 38 districts are Maoist-affected.

After Tuesday, the last round of elections will be held Nov 20. Votes will be counted Nov 24.