More than 10 million people cast ballots, on top of four million who voted early to decide the fate of over 1,600 candidates, including five of Indian-origin, contesting fromover 55 political parities.
In Sydney, 61-year-old Turnbull voted along with his wife Lucyat the Double Bay Public Schoolin his seat of Wentworth.
The polls will elect all 226 members including 150 members for the lower houseof the 45th parliament after an eight-week official campaign period following thedouble dissolution announcedby Prime Minister Turnbull in April.
The main contest is between Turnbull and his conservative coalition against a Labor opposition led by Shorten.
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Early results from east coast and south Australian polling booths indicate a neck-and-neck race between the two major parties.
The Australian Electoral Commission reported a 3 per cent swing to the Labor Party with around 20 per cent of the vote counted. It projected 63 seats to the coalition and 62 to Labor.
Minor party candidates are also taking seats and a hung parliament is possible, media reports said.
He said he was confident Labor could win.
"Labor is very competitive," he said, adding"I know that some of the conservative political papers have run their drum beat and whatever happens, the Liberals will win. The fact of the matter is that Labor's agenda has been speaking to the daily lives and experiences of Australians."
Turnbull, who called an early election partly to establish a new mandate for his government after ousting the unpopular Tony Abbott as conservative leader 10 months ago, repeated his call for voters to choose the Coalition and avoid a hung parliament.
A Newspoll published in The Australian showed Turnbull's Liberal/National coalition 50.5 to 49.5 per cent in front on a two-party basis.
Meanwhile, four men were reportedly arrested overnight and later released forallegedlydamaging polling booths in St Kilda area in Melbourne.