Police said a 52-year-old man was hacked to death with a cleaver as two groups clashed during voting in Murshidabad constituency in West Bengal state. The Congress party said he was a party worker and was attacked by supporters of the All India Trinamool Congress, a regional party governing the state.
Television images showed some people exploding crude bombs outside a voting station, leading to the clash between rival groups and leaving two other people injured.
Four people were killed in poll-related violence during the first phase of voting on April 11.
The voting for 117 parliamentary seats in 13 states and two Union Territories on Tuesday means polls are now half finished for 543 seats in India's lower house of Parliament. The voting over seven phases ends May 19, with counting scheduled to begin May 23.
The Election Commission was tabulating Tuesday's voting turnout. The New Delhi Television news channel put the voting percentage at around 66%.
The election is seen as a referendum on Modi's five-year rule. He has adopted a nationalist pitch in trying to win votes from the country's Hindu majority by projecting a tough stance against Pakistan, India's Muslim-majority neighbor and archrival.
The opposition is challenging him over a high unemployment rate of 6.1% and farmers' distress aggravated by low crop prices.
Modi voted in his western home state of Gujarat on Tuesday, though he is contesting a parliamentary seat from Varanasi, a city in the northern state of Uttar Pradesh.
In an apparent reference to the Easter Sunday attacks in neighboring Sri Lanka, Modi told reporters, "The weapon of terrorism is IED (improvised explosive devices) and the strength of democracy is voter ID (identification cards). I can say with surety that the voter ID is much more powerful than an IED."
Campaigning in the multi-phase election ends 48 hours before voting in a particular area. The voting is staggered to facilitate movement of security forces to oversee the election and avoid vote fraud.
Tuesday's voting is important for Modi's Bharatiya Janata Party, which won more than half of the 117 seats from the states voting Tuesday in the 2014 elections that brought it to power. The BJP's performance Tuesday will have a bearing on its bid to retain power in New Delhi.
Voting also took place in Wayanad constituency in southern Kerala state, one of the two seats that the president of the opposition Congress party, Rahul Gandhi, is contesting. His home bastion, Amethi, in Uttar Pradesh state will vote on May 6. Gandhi will give up one seat if he wins in both places.
Voting also was held for one seat in Indian-controlled Kashmir, with the polls there spread over three phases due to security threats. The unprecedented decision for the Anantnag seat came amid almost daily gunbattles, crackdowns and anti-India protests in southern Kashmir.
Armed police and soldiers patrolled deserted streets in Anantnag town, where residents mostly stayed indoors, heeding to a boycott call by Muslim separatists who say the elections are an illegitimate exercise conducted under military occupation. Many polling stations were empty except for troops and polling staff.
Modi has used Kashmir to pivot away from his economic record, playing up the threat of Pakistan, especially after the suicide bombing of a paramilitary convoy on Feb. 14 that killed 40 soldiers, in a bid to appear a strong, uncompromising leader on national security. The bombing brought nuclear rivals India and Pakistan close to the brink of war.
Opposition parties have consistently said that Modi and his party leaders are digressing from the main issues such as youth employment and farmers' suicides.
Kashmir is divided between India and Pakistan and both claim the Himalayan territory in its entirety. Rebels have been fighting Indian control since 1989. Most Kashmiris support the rebels' demand that the territory be united either under Pakistani rule or as an independent country, while also participating in civilian street protests against Indian control.
India's independent Election Commission intervened last week to block hate speeches by imposing a temporary ban on campaigning by some top politicians across political parties.
Uttar Pradesh's chief minister, Yogi Adityanath of Modi's BJP, was barred from campaigning for three days for making anti-Muslim speeches. He said a Hindu god would ensure the BJP's election victory, while the opposition was betting on Muslim votes.
Mayawati, a leader of the Bahujan Samaj Party who goes by one name, was punished for 48 hours for appealing to Muslims to vote only for her party. India's top court ordered strict action against politicians for religion and caste-based remarks.
Hindus comprise 80% and Muslims 16% of India's 1.3 billion people. The opposition accuses the BJP of trying to polarize the Hindu votes in its favor.
Associated Press writer Aijaz Hussain in Srinagar, India, contributed to this report.
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