A man with a knife has been arrested by police at Paris' Gare du Nord station.
The arrest comes amid heightened security after the attack in Paris and as France prepares to go to the polls.
The man was arrested immediately and no one was injured in the incident, a police official told the Associated Press.
Video online shows heavily armed police surrounding a prone man as people hurried past.
The Gare de Nord is one of the French capital's top transit hubs, serving the city's metro, suburban trains as well as intercity and high-speed trains like the Eurostar from London.
- Video report by ITV News Europe Correspondent James Mates
The aftershocks of the shooting central Paris reverberated around France as the country prepares to go to the polls in just two days.
Candidates declared campaigning at an end for the upcoming presidential election after the attack on Thursday night.
But National Front candidate Marine Le Pen sought to make political capital of the shooting in a country on high alert after numerous terrorist attacks.
She laid the blame on the government's weakness in the face of Islamic extremists, earning a strict rebuke from Prime Minister Bernard Cazeneuve.
First-round voting is set to begin on Sunday morning - and no opinion polls showing what impact, if any, the shooting had will be published before then.
The Paris gunman Karim Cheurfi was a loner with few interests in life, his former lawyer has said.
Jean-Laurent Panier described Cheurfi as an "extremely isolated" individual who passed near unnoticed while in detention in comments to BFM-TV.
Despite reports that the gunman may have been inspired by radical Islamist terrorists, Mr Panier said his client never discussed religion.
"His only conversations were about how to fill his daily life with video games," he said.
Prosecutors describe French national with a long history of violence and criminal offences but few obvious signs of radicalisation.Read the full story ›
The attacker in the Paris shootings was named as Karim Cheurfi by Paris prosecutor who said he carried a note expressing support for so-called IS during the attack.
French officials confirmed the identity of the gunman as well as reports that a note defending the terror group was found near his body after he was shot dead in a return of fire.
The policeman shot dead in by a gunman in central Paris last night has been named as Xavier Jugele by a French policing group.
The Flag! organisation of LGBT officers said that Mr Jugele would have turned 38 in May.
It also emerged that the officer was among those who responded to the deadly terror attack at the Bataclan concert venue in November 2015.
Mr Jugele attended the high-profile re-opening of the venue a year on, telling People magazine he had attended to "to defend our civic values".
He added: "This concert's to celebrate life. To say 'No' to terrorists."
- Video report by ITV News Correspondent Richard Pallot
French President François Hollande has condemned what he called the "cowardly killing" of a policeman on the Champs-Elysees in Paris.
The gunman - who was shot dead by security forces - has yet to be formally identified but is believed to be a local man.
Two other officers were also injured as one of the world's most iconic boulevards became a scene of terror just two days before one of the most tightly fought presidential elections in decades.
Presidential candidate François Fillon pledged to keep the country under a state of emergency while far-right rival Marine Le Pen called on the government to restore France's borders following the latest attack.
Donald Trump has said the shooting in Paris will have a "big effect" on France's upcoming presidential election.
The US president tweeted: "Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election!"
Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election!
In the wake of the shooting the French government has pulled out all the stops to protect Sunday's vote as the attack deepened France's political divide.
"Nothing must hamper this democratic moment, essential for our country," French Prime Minister Bernard Cazeneuve said.
A written note defending the so-called Islamic State was found next to the body of the gunman killed after he shot dead a police officer in Paris, Reuters has reported, citing a judicial source.
The hardline militant group has said it directed the attack, which also wounded two other police officers.
Two French officials have said that the Champs-Elysees gunman was detained in February for threatening police.
The officials - who spoke on the condition of anonymity - said the gunman was detained at the end of the month after speaking threateningly about the police, but later released due to a lack of evidence.
They also reported he was convicted of attempted homicide in 2003 in shootings on two police officers.
A man believed to be the principal attacker was shot dead at the scene, after a police officer was killed and two others seriously wounded.
A second man wanted in connection to the attack is reported to have handed himself into police.
The attack comes just days before France's presidential elections.