A known terror suspect wielding an automatic weapon shot and killed a police officer and wounded two others on Paris' iconic Champs-Elysees boulevard on Thursday night, terrifying the French capital just days before a presidential election in which security and Islamist extremism are major themes.

The so-called "Islamic State" (IS) jihadi group claimed responsibility for the attack, in which the assailant was killed by police.

While authorities did not confirm any links to IS, President Francois Hollande said he was convinced the incident along the world-famous shopping mile pointed to a terrorist attack.

France's anti-terrorism prosecutor, Francois Molins, said investigators had verified the identity of the 39-year-old shooter and raided his home in an eastern suburb of Paris. Investigators are trying to determine whether the assailant had any accomplices.

The unnamed gunman, who was known to authorities before Thursday's attack, had previously been the focus of an anti-terror probe, sources close to the investigation said. The assailant was arrested in February on suspicion of plotting to kill officers but was released due to lack of evidence. 

In 2005, he was convicted on three counts of attempted murder, two of which were against police officers. The charges dated back to 2001, when the attacker was fleeing from police in a stolen vehicle. He shot and wounded both officers before being apprehended and placed in custody. While incarcerated, he also seriously injured another officer who was escorting him from his cell, grabbing his gun and firing several times. 

France has been under a state of emergency since 2015 after a spate of Islamist militant attacks that have killed more than 230 people in the country in the past two years. The attack on the Champs-Elysees resembled two other recent attacks on soldiers providing security at high profile locations in Paris: one at the Louvre museum in February and another at Orly airport last month. 

Officials had feared another bloody attack ahead of the first round of a two-part presidential election on Sunday.

Read: What you need to know about the French presidential election

Thursday night's attack comes two days after police arrested two French nationals in possession of explosives and weapons in the southern city of Marseille. The two men are suspected of planning an attack to disrupt the campaign. 

The attack came as the 11 candidates were appearing on television, making their final election pitches to voters before Sunday. The television channel interrupted broadcast of the event to cover the attack, etching security issues into voters' minds.

Conservative Francois Fillon said he would cancel election events scheduled for Friday and said on television the next president must prioritize "the fight against Islamic totalitarianism."

Far-right candidate Marine Le Pen also canceled an event and used the attack to highlight her hardline positions on Islamist extremism and immigration.

"We must attack the ideology of this terrorism, which has been proliferating for years," she said on Twitter.

Centrist candidate Emmanuel Macron said he was in solidarity with law enforcement and offered his condolences to the family of the dead police officer.

Socialist Benoit Hamon tweeted his condolences and "full support" to police against terrorism.

cw/sms (AP, AFP, dpa, Reuters)