India's main opposition BJP is making hefty gains over the ruling Congress party as hundreds of millions of votes cast during its mammoth nine-phase general election are being counted.
The BJP is leading in 231 of 460 seats for which initial indications are available, while the ruling Congress party is leading in 48 seats.
Final results for the 543 seats are expected later on Friday.
Voter turnout was a record 66.38%, beating the previous 1984 poll record.
About 551 million votes from more than 1.8 million electronic voting machines are being tallied to determine the fortunes of 8,251 candidates.
The BBC's Pratiksha Ghildial in Delhi says there is a lot of excitement at the BJP headquarters.
There are giant TV screens to project the results, a huge media contingent and a brass band playing patriotic songs, our correspondent says. The entire building is covered with posters of Mr Modi and party flags.
The mood in the Congress office is, however, sombre, says the BBC Hindi's Divya Arya in Delhi.
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There are no supporters barring a family that is conducting prayers outside the building, our correspondent says.
The five week-long election witnessed political campaigns marked by bitter exchanges between the main contestants and parties.
Voting was held in nine phases for security and logistical reasons. With 814 million eligible voters, it is the world's biggest exercise in democracy.
The Election Commission said counting would be held at 989 centres and more than 1,100 observers would be deployed to supervise the process. Reports say hundreds of thousands of security personnel will be deployed to ensure it happens peacefully.
Exit polls released by Indian media organisations after the last round of voting on Monday all showed the BJP-led National Democratic Alliance (NDA) well ahead in terms of predicted seat wins, and the governing Congress party trailing badly.
Five of the six polls projected the NDA mopping up the 272 seats needed to form a majority in the 543-member parliament. Predictions for the 28-party alliance have ranged from 249 to a huge 340 seats.
All the polls projected that the BJP would win more than 200 seats - between 210 and 291- beating its previous high of 182 seats in the 1998 and 1999 elections.
But correspondents say exit polls are notoriously inaccurate in India, partly because of the size and complexity of the electorate. In the last two elections, they were inaccurate and over-estimated the BJP's gains.
On Thursday, BJP supporters in the southern city of Bangalore organised Hindu religious rituals to pray for Mr Modi's success and reports from several cities said party workers had been stocking up on sweets in anticipation of the party's victory.
The election pits Mr Modi's BJP against the Congress, led by Rahul Gandhi, the latest member of India's influential Nehru-Gandhi dynasty.
India's new anti-corruption Aam Aadmi (Common Man's) Party, which secured a spectacular result in local polls in Delhi last autumn, is challenging 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 government formation.
Among the key constituencies to watch are Varanasi - from where Mr Modi ran against Arvind Kejriwal of the Aam Aadmi Party (AAP) and Ajay Rai of the Congress party - and Amethi, the seat of the Congress party vice-president Rahul Gandhi. Mr Gandhi is being challenged by Smriti Irani of the BJP and Kumar Vishwas of the AAP. (BBC)
