It was what many feared most: a terrorist attack in the run-up to France's hotly contested presidential election on Sunday (April 23).
At around 9pm local time on Thursday, a 39-year-old man got out of a car on the famous Paris shopping boulevard, the Champs Elysees. Armed with an automatic assault rifle, he opened fire on a police van, killing one police officer and injuring two others before being gunned down in a firefight.
The incident was small compared with the terror attacks that the French have witnessed recently - often leaving dozens dead - but its timing in the midst of the country's most volatile election in years has raised alarm on already tense streets around the country.
The election remains a tight four-way race, with only one candidate, Ms Marine Le Pen, leader of the far-right National Front, considered a shoo-in for the second-round run-off. She has campaigned against immigration and for stronger security measures.
Pollsters Ifop say that 51 per cent of France's anti-terror police support the hardliner.
On Friday, she again called for France to reinstate border checks, in effect asking for the country to leave the Schengen free travel area, a key pillar of the European Union.
"My government of national unity will implement this policy, so that the Republic will live, and that France will live," she told a news conference.
The other contenders - centrist Emmanuel Macron, conservative Francois Fillon and leftist Jean-Luc Melenchon - are jockeying for a place in the two-person run-off polls. Currently, Mr Macron is the favourite by a narrow margin.
Many analysts remain divided on the impact of Thursday night's incident on tomorrow's polls, even though it would appear that Ms Le Pen is the obvious candidate who would benefit.
"It may also benefit Fillon's vote. We are all in a fog. Speaking frankly, we need a fortune teller, not a political analyst," Ms Nathalie Goulet, a centrist member of France's Upper House of Parliament, the Senate, told The Straits Times.
Mr Antoine Jardin, a researcher at France's prestigious Sciences Po university, noted that security has long been a core issue for French voters, not least National Front supporters.
The attack occurred during the final televised debate of the campaign, and Ms Le Pen told viewers that France needed a new plan to deal with terrorism "with new measures and with borders".
Mr Fillon told viewers that he was a man of experience, and his embattled campaign looks poised to benefit from the desire for a tough leader.
On Friday, Mr Fillon called for convicted terrorists to be stripped of their French citizenship.
However, commentator Caroline Fourest, who lost colleagues in the attack on satirical newspaper Charlie Hebdo, believes that it is difficult to predict voters' intentions, particularly because of the timing of the latest attack.
"It's more complicated because it's so soon before the vote, and usually, the first move after a terror attack is to stay calm and to unite," she said.
Ms Fourest also referred to tactical voting patterns, noting: "People who want to avoid Fillon and Le Pen will vote Macron. If the leftist voters want to defeat Le Pen they will vote Macron; Melenchon, if they still want to make a point."
The other two major candidates, Mr Macron and Mr Melenchon, however, are not seen as being strong on security issues.
The latest opinion poll by Elabe shows Mr Macron leading with 24 per cent and Ms Le Pen losing ground at 21.5 per cent. Mr Fillon was third, polling 20 per cent, and Mr Melenchon scored 19.5 per cent.
The opinion poll was conducted on Wednesday and Thursday just before the shoot-out on the Champs Elysees.