The news that a policeman had been shot dead on the famous Champs-Elysées avenue broke as the 11 presidential candidates were appearing live on TV in a show dubbed “15 minutes to convince” France.
The far-right Marine Le Pen had not long finished her 15-minute slot when it became clear that France had been hit by another jihadist attack against its forces of law and order. An attack quickly claimed by terror group Isis.
Authorities had long feared an Isis-inspired or organised attack in the run-up to the election, as it would represent not just a symbolic attack on democracy, but also a chance to perhaps influence the result to their liking, with a victory for Le Pen fitting in with their desire to divide France's communities.
Hence the reason the government extended the state of emergency to cover the campaign.
The immediate impact of Thursday night's attack saw Marine Le Pen, François Fillon and Emmanuel Macron announce they were suspending their campaigns. They all cancelled meetings on Friday, the last official day of campaigning.
Although events have been cancelled the candidates haven't quite gone quiet.
Marine Le Pen, who has seen her campaign tail off in recent weeks launched an attack on previous governments.
"This war is being waged without mercy and without respite," she said in a statement at her headquarters.
"Everyone will understand that we can not lose it, but for the last ten years, under the governments of the Right and the Left, everything was done for us to lose it," she said.
Far-left Jean-Luc Mélenchon refused to cancel his last day of campaigning, not wanting to give the terrorists the last word or allow them to “disturb our democratic process”. Macron and Hamon are due to give speeches later.
Most candidates pledged their immediate support to the country's police force, who have once again lost a colleague to a coldblooded terrorist assault.
Both Macron and Hamon urged the French public not to “give in to fear”, a familiar call in recent years.
And what about the voters?
With no major attack in France since Nice in July last year the issue of terrorism and security had been relegated down the order of top priorities for voters.
Finding a way to boost the country's sluggish economy and cut unemployment had become the number one concern for voters, but experts and candidates alike feared that would change if there was further bloodshed.
Even before Thursday's attack Marine Le Pen has sought to push the issue of terrorism back to the forefront this week arguing that the attacks in Nice and at the Bataclan would not have happened under her watch.
Those statements were ridiculed by many.
In all the analysis of whether Le Pen could pull off another shock populist election victory experts had said it was unlikely, but had all warned that an "outside event" such as a terror attack could boost her support, given she is seen as being the most uncompromising on how to deal with the terror threat against France. Even without campaigning she has made her positions clear: close the borders, expel suspects, and strip them of French nationality (if they are dual nationals).
US president Donald Trump, whose own populist victory was celebrated by Marine Le Pen reckoned that attack will have a "big impact" on the poll.
"Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big impact on presidential election," Trump tweeted. Was he suggesting a boost for fellow populist Le Pen?
Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election!- Donald J. Trump (@realDonaldTrump) April 21, 2017
Some suggest former PM François Fillon, a man with experience during a crisis could also benefit, while neither newcomer Macron nor Melenchon are seen as being strong on the subjects of terrorism and security.
But French political expert Bruno Cautres from the Cevipof think tank says the impact on voters will be minimal.
“I don't think it will change much at this late stage,” Cautres told The Local. “The campaign has been running for months now and most voters know the candidates they will vote for.”
Cautres accepted however it could reinforce those undecided voters who were tempted to vote for either Marine Le Pen or François Fillon.
The danger for Marine Le Pen is that she could face a backlash if, as she has done in the past, she tries to make political gain so soon after the distressing killing of a French policeman.
“She cannot give the impression she is trying to profit from this,” Cautres said. “Candidates would have to show they are the ones who can unite French people and bring them together.”
But as already shown, Le Pen, who is no longer guaranteed a place in the second round run off, will not hold back.
Jean Yves Camus a specialist on the French far right told The Local that an attack on a policeman that was over almost as soon as the news broke does not have the same kind of traumatic impact on the public as the mass killings in Nice or Paris in November 2015.
“Psychologically it's not the same. We knew the number of victims on the Champs Elysées very quickly but at the Bataclan we had to wait hours without knowing," Camus said.
Two weeks after those Paris terror attacks in 2015 Marine Le Pen achieved her highest ever vote count when some 6.8 million French voters backed her in the regional elections.
But as Camus pointed out, it was still not enough votes for her to win any of the regions outright.
If Le Pen makes it to the second round against inexperienced Macron, she probably won't be able to resist trying to steer the debate away from the economy and towards terrorism, even if it looked like she was profiting from another terror attack.
But even if she did opinion polls still suggest she would still be well beaten by whichever rival she faces on May 7th.
The attack will now mean France will go to the polls on Sunday nervous about further attacks but many hope it will have a positive impact on the election by pushing more people to vote to send the message that the country's democracy is strong.