France goes to the polls on Sunday under heavy security in a presidential election clouded by a threat of more terrorism like the attack that left a policeman and his killer dead on the Champs-Elysee in Paris on Thursday.

Some 50,000 police officers and gendarmes, and 7,000 soldiers, will be on duty throughout the country amid fears that ISIL or its sympathisers may try to mount another operation.

Police officer Xavier Jugele, 37, was shot dead and two colleagues were wounded, along with a female German tourist, when 39-year-old Karim Cheurfi opened fire with an assault rifle on a police vehicle.

The shooting caused panic among the crowds on one of the world’s most famous avenues. Shoppers, restaurant diners, cinema-goers and spectators at a cabaret show were unable to leave for two hours after the shooting, which happened around 9pm local time.

One witness who gave his name as Chelloug, a kitchen assistant, said he was leaving a shop when he saw a man get out of a car and open fire with a rifle on a policeman.

“The policeman fell down,” he said. “I heard six shots, I was afraid. I have a two-year-old girl and I thought I was going to die ... He shot straight at the police officer.”

ISIL quickly admitted it carried out the murder via its online propaganda agency Amaq, calling Cheurfi a “soldier of the Caliphate”.

But it also named him as Abu Yusuf Al Bejiki, indicating he was Belgian. But the name was unknown to the Belgian authorities, raising suspicion among investigators, and some security analysts, that this was an opportunistic claim of responsibility.

Cheurfi was a French national with a history of violence, including previous attacks on police officers in 2001 which earned him a 20-year jail sentence — later reduced to 15 — for attempted murder.

A pump-action shotgun and knives were recovered from his car. Investigators also found a copy of the Qu’ran — though there is no evidence he had shown serious interest in religion — and a document referring to ISIL. During a news conference, antiterrorism prosecutor Francois Molins said the document — described as a note defending ISIL — apparently fell out of Cheurfi’s pocket.

The GPS system of his car revealed entries for the addresses of arms suppliers, the headquarters of a French intelligence agency and a police station in Seine-et-Marne, the area on the outskirts of Paris where he was born and lived.

Some reports suggested the authorities had become aware of encrypted online activity in which he spoke of wanting to kill police officers, but when questioned by police, in February, he apparently showed no signs of radicalisation and there was insufficient evidence to prosecute him.

Three members of his family were questioned yesterday. Cheurfi lived with his mother in the multi-ethnic suburb of Chelles, a 30-minute train journey east of Paris, where neighbours described him as a friendless oddball who seemed “like he was from Mars”.

“Everyone knew him here,” said one. “He was someone who had lost all reason, who was psychologically very damaged.”

Another local man, 2-year-old Abdel, said Cheurfi had been influenced by his repeated experiences in prison. “He hated the police and France,” he said.

Salim, a family acquaintance, said Cheurfi never went to mosque and was “nuts” and “could hardly use a remote controller for the television. Go on the internet and contact Daesh (Islamic State)? I can’t see it.”

The murdered policeman was among the officers who responded to the gun and bomb attack on Bataclan concert hall in Paris in November 2015, the most murderous of a wave of the attacks on Paris, which killed 130 people. Jugele was there again a few days before the first anniversary of the attack when the venue reopened with a concert headlined by Sting. In an interview with People Crime, a US website, he told of how happy he was to be at the “symbolic” reopening, saying, “We’re here tonight as witnesses, to defend our civic values. This concert is to celebrate life. To say `No’ to terrorists.”

The French president Francois Hollande visited the hospital where Jugele’s two wounded colleagues were treated. They, and the injured German tourist, were said to be out danger.

The attack, coinciding with the final televised debate featuring all 11 candidates in the first round of the election, came two days after two men were held in the southern city of Marseilles for allegedly planning a terrorist attack on the election campaign.

An arsenal of guns and explosives was found in a flat rented under false names by 29-year-old Mahiedine Merabet and Clément Baur, 23, who converted to Islam in his mid-teens.

Both have criminal records and although their past offences were not connected to terrorism, they were known to the intelligence services, having become radicalised while in jail together.

Although no specific target or even location was confirmed, French media speculated that the men may have been planning to attack the centre-right candidate Francois Fillon. Police distributed their photographs to the security personnel protecting the candidates who were thought to be potentially at risk.

Mr Fillon said yesterday that if elected, he would seek a global coalition — controversially including not only the United States but Russia to fight “Islamist totalitarianism”.

“My foreign policy would be focused, in priority, on destroying Islamic State [ISIL],” he said. “This will only be possible the day the major powers will truly act together ... From Washington to Moscow, I will take the initiative of an international coalition against Islamist terrorism”.

Mr Fillon has been criticised by opponents for his friendly attitude towards Vladimir Putin’s Russia, but said: “The more the United States, Europe, Russia, Iran, Turkey and the Gulf countries are divided, the more victory against Islamist totalitarianism will be postponed.”

Tomorrow’s first round of voting is not expected to produce an outright winner but the two leading contenders will then fight a deciding second round two weeks later, giving the police and intelligence service more security headaches as they seek to guard against the possibility of further attacks.

foreign.desk@thenational.ae with additional reporting by * Agence France-Presse