Jean-Francois Ricard, France's chief anti-terrorist prosecutor, said the attacker was a Tunisian born in 1999 who had arrived in the Italian city of Bari on October 9.
A man armed with a knife has attacked people inside a French church and killed three, prompting the government to raise its security alert to the maximum level hours before a nationwide coronavirus lockdown.
The man suspected of killing three people in a French church arrived by train carrying an Italian Red Cross identity document, changed his clothes at the train station, then walked to the church to begin his attack, a prosecutor said on Thursday.
Jean-Francois Ricard, France's chief anti-terrorist prosecutor, said on Thursday the attacker was a Tunisian born in 1999 who had arrived in the Italian city of Bari on October 9.
The prosecutor said the man had been caught on video surveillance at the railway station in Nice, and from there had walked the 400 metres to the Notre Dame church.
France has raised its alert to the highest level nationally after a knife-wielding man killed three people at a church in the city of Nice.
Within hours of the Nice attack on Thursday, police killed a man who had threatened passersby with a handgun in Montfavet, near the southern French city of Avignon and authorities in Lyon took a suspect armed with a knife into custody.
'As cowardly as it is barbaric'
Prime Minister Jean Castex said the Nice attack, in which at least one victim had their throat slit, was "as cowardly as it is barbaric" and told parliament he had decided to raise France's Vigipirate security alert system to the highest, "attack emergency" level.
French anti-terror prosecutors have opened an inquiry into Nice, the third one since a trial opened in September for the 2015 attacks at the offices of satire magazine Charlie Hebdo and a kosher supermarket linked to Daesh and al Qaeda.
Hebdo's caricatures of Prophet Muhammad, cited as motive in the 2015 attack, as recently as October reemerged as a flashpoint issue in France's ties with the Muslim world.
What we know so far
A man and a woman died at the Basilica of Notre-Dame, in the heart of the Mediterranean resort city, while a third person succumbed to injuries later, a police source told AFP.
No mass was underway at the time of the attack, but the church opens around 0700GMT and "people come in to pray at all hours", Father Philippe Asso, who serves at the basilica, said.
As he did every day, the sexton the church opened up the doors around 0730GMT. The first Mass of the day was not due to start for another two hours.
But by around 0800GMT, a man armed with a knife entered the church and slit the throat of the sexton, partially beheaded an elderly woman, and badly wounded a third woman.
The sexton and the elderly woman died on the spot, the third woman managed to make it out of the church into a nearby cafe, but she died from her wounds, Nice Mayor Christian Estrosi told reporters at the scene.
Daniel Conilh, a 32-year-old waiter at the Grand Cafe de Lyon, a block from the church, said it was shortly before 0800GMT am when "shots were fired and everybody took off running."
"A woman came in straight from the church and said, 'run, run, someone has been stabbing people'," he said, and dozens of police and rescue vehicles quickly sealed off the neighbourhood.
Estrosi, who described the attack as terrorism, tweeted that police had detained the attacker.
"The suspected knife attacker was shot by police while being detained. He is on his way to hospital. He is alive," Estrosi told reporters.
The suspect was later identified as 21-year-old Tunisian Brahim Aouissaoui, a Tunisian security source and a French police source said.
Aouissaoui is originally from the village of Sidi Omar Bouhajla near Kairouan, but had lately been living in Sfax and police visited his family there on Thursday, the Tunisian source said.
The other attacks reported on Thursday in Lyon and in the Saudi city of Jeddah at the French consulate were not immediately linked to the attack in Nice.
French police shot dead a man who claimed allegiance to an anti-immigrant group in Montfavet, near the city of Avignon in southern France, after he had earlier threatened passersby with a handgun, police said, confirming media reports.
The official said the man claimed to belong to extreme-right group Generation Identity and had assaulted a local merchant.
A man armed with a long knife was arrested in the southeastern French city of Lyon as he attempted to board a tram, local media and Lyon's district mayor said.
The suspect, an Afghan national in his 20s, had already been flagged to French intelligence services, the reports said.
Condemnations and support pour in
Condemnation came from the pope and European leaders as well as from Turkey, which is involved in a heated diplomatic spat with Paris over cartoons mocking the prophet.
Pope Francis condemned the attack as "savage" and the Vatican said terrorism and violence were never acceptable.
European Union leaders expressed solidarity with France as well, and pledged to confront "those that seek to incite and spread hatred."
"I condemn the odious and brutal attack that has just taken place in Nice and I am with France with all my heart," European Commission president Ursula von der Leyen tweeted.
Ankara strongly condemned the savage knife attack, offering its "solidarity" despite a running diplomatic spat with Paris.
"We strongly condemn the attack committed today inside the Notre-Dame church in Nice," a Foreign Ministry statement said, while offering condolences to the victims' relatives.
Inflamed tensions with Muslims
Since the Hebdo murders, a wave of attacks on French soil, often by so-called "lone wolf" assailants, has killed more than 250 people.
On October 16, school teacher Samuel Paty was beheaded for showing Hebdo's caricatures of Prophet Muhammad, which Muslims consider to be blasphemous, to his students in a class on civics.
Muslims' objections to the Hebdo caricatures also include the complaint that they were meant to insult all Muslims and are often seen in the larger context of a rising anti-Islam sentiment in the country, with successive French governments introducing laws that have targeted Muslims for practices such as eating halal food and women wearing the hijab.
The Nice assault prompted lawmakers in parliament to hold a minute of silence, before Castex and other ministers abruptly left for an emergency meeting with President Emmanuel Macron.
The French authorities are treating it as a terror attack, with the anti-terrorist prosecutor immediately opening an inquiry into "murder and attempted murder linked to a terrorist enterprise".
Since Paty's killing, French officials – backed by many ordinary citizens – have re-asserted the right to display the cartoons, and the images have been widely displayed at marches in solidarity with the killed teacher.
That has prompted an outpouring of anger in parts of the Muslim world, with many governments accusing French leader Macron of pursuing an anti-Islam agenda.
Protests against Macron and anti-Islam policies have taken place from Bangladesh to Gaza in recent days. Stories across the Arab world have pulled French products, and leaders, including Turkey's President Recep Tayyip Erdogan, have asked for a boycott of products made in France.
READ MORE: Erdogan: No true Muslim can be a terrorist