April 2017 Champs-Élysées attack

Following Cheurfi's identification, three members of his family were arrested in Chelles in the early morning of 21 April, although investigators believe Cheurfi acted alone and was inspired by ISIS but was not necessarily a member. In January 2018, his father, Salah Cheurfi, was sentenced to 18 months in prison for having made comments of support for terrorism.

On 20 April 2017, three French National Police officers were shot by Karim Cheurfi, a French national wielding an AK-47 rifle on the Champs-Élysées, a shopping boulevard in Paris, France. One officer, French National Police Captain Xavier Jugelé, was killed and two other French National Police officers and a German female tourist were seriously wounded. Karim Cheurfi was then shot dead by police. Amaq News Agency, which is linked to the Islamic State of Iraq and Syria (ISIS), claimed the attacker was an ISIS fighter. French police and prosecutors are investigating the attack as terrorism, and have launched a counter-terrorism prosecution.

The attacker was identified as French national Karim Cheurfi, who had an extensive criminal record that included a conviction and a twelve-year prison sentence for an earlier attempt to murder two police officers. Police found a note praising ISIS, along with addresses of police stations, on his body. Because the attack took place immediately before the country's 2017 presidential election, media reports commented on its possible influence in the election's tone.

The officer who was assassinated was 37-year-old Xavier Jugelé, who was murdered outright by two gunshot wounds to the head. He was one of the officers to respond to the Bataclan theatre during the massacre there in November 2015. Jugelé had been a member of the Paris police force since 2010, and was known as a gay rights activist and member of FLAG, the French association for LGBT police officers. He had been interviewed by the BBC in November 2016 when he visited the Bataclan when it reopened. He also served twice in Frontex to assist in the European migrant crisis in Greece. Jugelé was posthumously promoted to captain and awarded the knighthood of the Legion of Honor. He was eulogized by his civil partner Etienne Cardiles. President François Hollande, Emmanuel Macron and other dignitaries were at the national ceremony of honor which took place at the Paris Police Prefecture on 25 April 2017. Cardiles later attended the installation of President Emmanuel Macron at the president's invitation. Cardiles married Jugelé posthumously on 30 May.

He had been detained in February 2017 for allegedly making threats to kill police, but was released due to lack of evidence. No evidence of radicalization was found, and he was never placed on a terror watch list. He was, however, added to a "radicalisation and terror prevention and alert list" created in the wake of the Charlie Hebdo shooting, but he was not considered a priority. CNN reported that a source close to the investigation said police had launched a counter-terrorism investigation in March 2017 after learning of his attempts to establish communication with an ISIS fighter. AFP reported that police were aware of an attempt by Cheurfi to buy weapons in early 2016, with the intent of using them to kill French police officers in retaliation for the deaths of children in the Syrian Civil War. His home in Chelles was searched after the attack.

At the time of the shooting, France was on high alert in the wake of the attacks in Paris in November 2015 and in Nice in July 2016, as well as in anticipation of the first round of the 2017 presidential election, which was scheduled in three days. Since 2015, there had been a spate of Islamist terrorist attacks on French police officers, soldiers and civilians, resulting in the deaths of more than 230 people. Two men were arrested in Marseille two days before the shooting, for allegedly planning a terrorist attack.

Bernard Cazeneuve, the French Prime Minister, criticized Le Pen's and Fillon's responses. He accused Le Pen of trying to exploit the shooting for politics and attacked her for demanding further security measures. He explained that she had voted against the government efforts on security previously, referring to her party voting against an anti-terrorism law in 2014 and against beefing up of resources for French intelligence services in 2015. He criticized Fillon's record on security during his term as Prime Minister.

At the time of the shooting, Cheurfi was already well known to the DGSI, France's domestic security service. He had an extensive criminal record for violent robberies and a shooting in 2001, in which he shot two police officers when they pulled him over. He wounded one of the officers after grabbing his gun while he was being questioned. He was convicted of attempted murder in 2005 and he was sentenced to twenty years in prison, which was later shortened to fifteen years. Despite a history of violence while behind bars, he was released in October 2015.

Amaq News Agency, which is linked to the Islamic State (ISIS), said the shooter was an ISIS fighter, giving his pseudonym as Abu Yusuf al-Beljiki. The claim suggested the attacker was from Belgium. News outlets commented that the timing of the claim was "unusually swift". French police identified the attacker as 39-year-old Karim Cheurfi, born in Livry-Gargan in 1977 and living in Chelles, east of Paris. French prosecutors said that a note praising ISIS fell out of his pocket after he was shot, and that he was carrying addresses of police stations.