France on Friday was warned to brace for more "terrible attacks" at home and abroad in the wake of this week's Nice murders as police overpowered a man in Paris when he threatened officers with two knives.
The latest arrest came after police received an alert that a man armed with a knife was knocking on his neighbour's door in a south-western district of the capital. Officers used a Taser and rubber bullets to overpower him.
While his motive was unclear, the incident further frayed French nerves ahead of All Saints weekend in the wake of the attack at a church in Nice, in which three people - a man and two women - were stabbed to death.
Brahim al-Aouissaoui, 21, from Tunisia, beheaded one 60-year-old woman at the Riviera city's Notre-Dame Basilica on Thursday morning, slit the throat of sexton Vincent Loquès, 55, and inflicted multiple stab wounds on Simone Barreto Silva, 44, a Brazilian mother-of-three.
He was Tasered and then shot 14 times by police who arrived on the scene when the alarm was raised. He is being treated in hospital and is still in a critical condition. Police on Friday detained and questioned a 47-year-old man believed to have been in contact with the assailant the night before the attack.
It came as Gerald Darmanin, the interior minister, warned on Friday that more attacks on French soil were likely as the country was engaged in a "war against Islamist ideology".
"We are in a war against an enemy that is both inside and outside," he told RTL radio after a defence council meeting. "We need to understand that there have been and there will be other events such as these terrible attacks."
This was the third in less than two months following the beheading of a teacher outside Paris who had shown caricatures of the Prophet Mohammed in class after the images were republished by satirical newspaper Charlie Hebdo.
France is to increase the number of soldiers deployed to protect schools and religious sites from around 3,000 to 7,000. Some had already arrived in Nice, along with 120 police reinforcements. In shock, locals on Friday braved a nationwide Covid lockdown to pay their respects before the Basilica. Many sang The Marseillaise, France's national anthem, before observing a minute's silence.
Aurélie Jolie Amami was a friend of Mr Loquès. "I was supposed to be there that morning but I overslept," she told The Daily Telegraph.
"Vincent was someone very kind. I knew his mother, his wife and two daughters, around the age of my girls - 18 and 19. They were friends."
Jean-François Gourdon, treasurer of the Basilica, said: "I saw Vincent that morning. We had coffee opposite. For once, I left early. I have a lot of anger. Vincent was always so full of compassion and joie de vivre. We're becoming a Lebanon with all these fanatics. You see how that turned out? We don't want to become Europe's Lebanon."
On Thursday night, around 200 black-clad protesters from far-Right group Génération Identitaire marched in central Nice and laid flowers before the church before shouting "This is our home" and "Islam out of France".
Jean-Yves Le Drian, the French foreign minister, warned that citizens faced a security risk "wherever they are" in the wake of the attack, saying alerts had been sent to all French nationals abroad. His comments came as tens of thousands of Muslims protested in Pakistan, Bangladesh and Palestinian territories on Friday against Mr Macron's perceived Islamophobia.
In London, British Muslims gathered outside the French embassy and shops including Louis Vuitton to denounce Mr Macron for his backing of the right to publish cartoons of the Prophet Mohammed, something many Muslims consider blasphemous.