Indian authorities on Wednesday banned large gatherings in a violence-hit town amid crucial regional polls that have seen supporters of rival parties clash in the streets and left dozens dead in recent months.
Thursday's second day of polling in West Bengal state, home to 90 million people, is central to a massive push by Prime Minister Narendra Modi's Hindu nationalist party to oust state leader Mamata Banerjee, a fierce critic of the government.
Banerjee, a 66-year-old firebrand whose Trinamool Congress party ended three decades of communist rule in the state in 2011, is contesting the election in Nandigram against a former confidante who defected to Modi's Bharatiya Janata Party last year.
The high-stakes showdown in a state notorious for political violence saw the Election Commission ban gatherings of more than four people in a bid to ensure safety for voting, officials said.
"It's battle royale in Nandigram," an election official in Kolkata told AFP.
Several thousand paramilitary troops were deployed to the town, an Election Commission observer added.
Dozens of people have died in political violence in recent months.
On Tuesday, Indian cricketer turned BJP candidate Ashok Dinda blamed political opponents for a brick thrown at his car.
Dinda said he had to flee from dozens of opponents and suffered injuries, with authorities tightening security around the former bowler after the incident.
Polls are being held in West Bengal over eight phases amid tight security and conclude on April 29.
Results will be announced on May 2, alongside several other state and territory elections in Assam, Kerala, Tamil Nadu and Puducherry.
Facebook has meanwhile promised to combat hate speech and misinformation across several fiercely contested states.
The social media giant said that it was working to reduce the risk of "problematic content going viral in these states and potentially inciting violence" in the elections.
"We recognise that there are certain types of content, such as hate speech, that could lead to imminent, offline harm," the company said in a statement on its website.
Twitter said last week as the polls kicked off that it had expanded its team to block attempts to "manipulate the platform and content that can incite violence, abuse, and threats and trigger the risk of offline harm".