The six seats where polling would be held were Valmikinagar, Paschim Champaran, Purvi Champaran, Vaishali, Gopalganj(SC) and Siwan.
Elaborate security measures are in place with 58,000 security personnel deployed.
Armed personnel would be posted at every polling location.
The Election Commission has reduced poll timings by two hours in five assembly segments in view of Maoist threat.
