Indians are voting in the biggest day of the general election pitting the ruling Congress party against the main opposition BJP.
Nearly 200 million voters are eligible to cast their ballots in 121 seats in 12 states, including Karnataka, Rajasthan, Uttar Pradesh and Bihar.
The nine-phase vote began on 7 April 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.
Polling has been already completed in 111 seats, and voter turnout in most states has been higher than in 2009.
Thursday is one of the most critical days of voting spread across 12 states, from Indian-administered Kashmir in the north, to the information-technology hub of Bangalore in the south, Rajasthan in the west and the tea-growing Himalayan town of Darjeeling in the east.