Tens of thousands of armed police were on duty Monday as a restive Indian state wracked by violence went to the polls.
Maoist militants have unleashed a string of deadly attacks ahead of the vote in mineral-rich Chhattisgarh, one of India's poorest states, killing 13 people in recent weeks.
Hours before voting began, insurgents blew up an improvised explosive device in Kanker district on Sunday, killing a police officer.
The Maoists, who say they are fighting for the rights of local tribes and poor farmers, have put up posters across the state urging voters to boycott the polls.
The vote -- one of five state elections this month and next ahead of 2019 general elections -- is staggered because of the violence, with a second round on November 20.
"Some 100,000 security personnel, including central paramilitary force, have been deployed to ensure peaceful polling in the first phase," said senior police officer D. M. Awasthi.
Election officers were airlifted to the most volatile areas where landmines planted by Maoists are a common threat, he said.
The state has been governed by Prime Minister Narendra Modi's Hindu nationalist Bharatiya Janata Party (BJP) for 15 years.
Chief Minister Raman Singh is seeking a fourth term and has blamed the rebels for impeding development projects in the state, home to around 25 million people.
Maoist groups are believed to be present in more than 10 states across India.
But they are most active in remote parts of Chhattisgarh, Odisha, Bihar, Jharkhand and Maharashtra, where much of the population remains mired in poverty and lacks access to critical services.
The left-wing insurgency began in West Bengal state five decades ago when peasant farmers rose up against feudal landlords. Some 10,000 people have been killed since.
The military strategy of the Maoists, also known as Naxals, is loosely based on the Chinese revolutionary leader Mao Zedong.
Before the end of the year elections will also be held in the states of Mizoram, Madhya Pradesh, Telangana and Rajasthan. Results will be announced for all on December 11.