Voters prepare to cast their ballots at a polling station in Henin-Beaumont, France, on April 23, 2017. (Xinhua/Chen Yichen)

PARIS, April 23 (Xinhua) -- Millions of French voters began casting their ballots in the first round of the presidential election Sunday morning amid an atmosphere of uncertainty.

Polling stations at France's European continent opened at 8 a.m. (0600 GMT) and will run for a maximum of 12 hours. Those in the largest cities will close at 8 p.m. (1800 GMT). In France's oversea territories, the voting was held on Saturday.

The voting will winnow down a list of 11 candidates to two finalists for a runoff vote scheduled for May 7, if no one wins by at least 50 percent in the first round.

Out of the 11 candidates, four remain frontrunners in previous polls, namely the centrist former Minister of economy Emmanuel Macron, the far-rightist Marine Le Pen, the right-wing conservative Francois Fillon and the far-leftist Jean-Luc Melenchon.

At the No. 17 polling station in the 17th arrondissement of Paris, a voter, Marine, who runs a magazine, told Xinhua that she has just voted for Macron.

"It's been five years since the left came in power and the result is disappointing. Why not give Macron a chance? France is facing a number of problems, including security and economy. I expect a united France," she said.

At a polling station in Henin-Beaumont, a commune in north France where far-right candidate Marine Le Pen voted, voter Alexandre said the proposals by the candidates all seem wonderful but he expects whoever wins to keep their promises to ensure the country's security and boost growth.

Macron and Le Pen both casted their votes in the morning, while Fillon and Melenchon are both expected to vote around noon.

Outgoing President Francois Hollande also casted his ballot at around 10 a.m. local time in Tulle in central France, where he served as the mayor from 2001 to 2008.

Nicolas, a voter who backed the Socialist leader five years ago, said "I don't like the extremes. I don't appreciate neither the centre right candidate nor the one of the Socialist party."

Forty-one-year-old Nathalie voted for conservative five years ago and said she was so upset by Fillon's "fake jobs" scandal. She only made her mind up this morning before going to the polling station.

"Which candidate will I choose? I have asked this question for months without being able to find an answer. I was confused," she said.

Unlike the 2012 presidential contest which was a clear race between the left and the right, political landscape is blurred for this election's first leg as all scenarios are expected, according to analysts.

In a further challenge for candidates, a third of voters are undecided, which could lead to high voter abstention.

"We choose a president to defend the interests of all inside and outside the country. Unfortunately, I noted that for years the French interests have not been taken into account. So, for me, abstention is the solution," said Laurent, a worker at Charles De Gaulle airport.

TIGHTENED SECURITY

This time, French citizens are voting under tightened security after terrorism woes re-emerged in the wake of a shooting targeting police officers in the French capital.

On Thursday, an armed man, in an attack claimed by the Islamic State (IS), shot dead a policeman and wounded two other before being killed in the Champs Elysees avenue. The attack came only some 48 hours after police held two individuals in Marseille, south France "on suspicion of planning violent act on the eve of presidential election." Several weapons, including a machine gun and two hand guns in addition to bomb-making materials were found during a police raid in an apartment they had rented in the French city.

According to local reports, main presidential candidates had been warned of the risk of an eventual attack.

Le Parisien newspaper on Saturday reported French government security authority the Central Directorate of Public Security had circulated a note saying "the jihadist threat" during the elections was "constant and pregnant."

"The police presence during the opening of the polling stations is essential," it said.

A total of 50,000 policemen and gendarmes will be mobilized during the two rounds of presidential elections on April 23 and May 7, French Interior Minister Matthias Fekl said.