Millions of Indians have begun voting on the first big day of the general election pitting the ruling Congress party against the main opposition BJP.
Polling is being held in 91 seats in 14 states, including in the capital Delhi and the key state of Uttar Pradesh.
The nine-phase vote began on Monday and will conclude on 12 May. Votes will be counted on 16 May.
More than 814 million Indians are eligible to vote in the polls.
Two soldiers were killed and three others injured in a landmine explosion blamed on Maoist rebels in Jamui, a rebel stronghold in the eastern state of Bihar, police said.
The blast occurred before polling began, but voting has remained unaffected in the area.
Voters have turned out enthusiastically to cast their ballots in the politically crucial northern state of Uttar Pradesh which sends the maximum number of MPs to the parliament, says the BBC Hindi's Nitin Srivastava in Muzaffarnagar.
Some 16 million voters are eligible to cast their ballots in 10 constituencies in the state that go the polls today.
They include the restive Muzaffarnagar constituency, where at least 65 people were killed and 51,000 people - mostly Muslims - were displaced after Hindu-Muslim clashes in September.
Our correspondent says a number of displaced people living in camps in the area turned up to vote early on Thursday.
The BBC's Geeta Pandey in Delhi says voters at a school in the Sarvapriya Yihar district began queuing as polling opened at 07:00 (01:30 GMT).
Soon, several dozen people had queued up to cast their votes and the lines were getting longer by the minute.
Officials checked their names on the list and put the indelible ink on their forefingers.
The anti-corruption Aam Aadmi (Common Man's) Party, which secured a spectacular result in local polls in Delhi last year, offers a challenge to the main parties.
Several smaller regional parties are also in the fray and if no single party wins a clear majority, they could play a crucial role in the formation of a government.
The marathon vote is being staggered over five weeks for security and logistical reasons.
The third phase of the election on Thursday is the first big day of voting.
Polling is being conducted in all seven constituencies of Delhi, all 20 seats in the southern state of Kerala and 10 seats each in Uttar Pradesh, Maharashtra and Orissa.
Thousands of police and paramilitary security personnel have been deployed to ensure polling passes off peacefully.
On the first day of voting on Monday, polling took place in six constituencies in two states in the north-east - five in Assam and one in Tripura.
In the second phase on Wednesday, voting was held in six seats across four states.
The Lok Sabha (lower house of parliament) has 543 elected seats and any party or a coalition needs a minimum of 272 MPs to form a government.
Some 814 million voters - 100 million more than at the last elections in 2009 - are eligible to vote at 930,000 polling stations, up from 830,000 polling stations in 2009.
Electronic voting machines are being used and will, for the first time, contain a None of the Above (Nota) button - an option for voters who do not want to cast their ballot for any of the candidates.
The main contest in the elections is between the Congress, led by Rahul Gandhi, the latest member of India's influential Nehru-Gandhi dynasty, and the BJP, led by the charismatic and controversial Hindu nationalist leader Narendra Modi.
Modi, who is ahead in all the pre-election opinion polls, is the leader of Gujarat state, which witnessed one of India's worst anti-Muslim riots in 2002.
The BJP has promised to improve the economy and infrastructure and curb corruption if it wins in the general elections.
The party launched its manifesto hours after polling began for the first phase.
The Congress party has promised "inclusive growth" if it returns to power.
In its election manifesto, the party promised a raft of welfare schemes, including a right to healthcare for all and pensions for the elderly and disabled.