A woman has been beheaded, two others killed at a church in Nice. Photograph:( Twitter )
Three people were killed in the knife rampage Thursday in the Notre-Dame Basilica that prosecutors say was carried out by a young Tunisian recently arrived in Europe
French Prime Minister Jean Castex called radical political Islamism the country's enemy in an interview on Sunday.
Castex said ''An enemy has declared war on France. This enemy has been named and is known. It's called radical political Islamism. And this enemy is going to find us (standing) in its way."
Three people were killed in the knife rampage Thursday in the Notre-Dame Basilica that prosecutors say was carried out by a young Tunisian recently arrived in Europe.
It was the latest attack in France to be described by the government as an act of "Islamist" terror, in the wake of the republication of cartoons of the Prophet Mohammed by the Charlie Hebdo weekly in September.
In Nice, three men were released from police custody on Sunday after authorities determined they were not linked to the suspected attacker Brahim Issaoui, a source close to the investigation said.
Three men remain in custody, including a 29-year-old Tunisian suspected of migrating with Issaoui from their homeland to France.
Interior Minister Gerald Darmanin said that Issaoui "had clearly gone there (to Nice) to kill".
"Otherwise how can we explain why he armed himself with several knifes having only just arrived?... He clearly did not come just to get his papers," Darmanin told the Voix du Nord newspaper.
Investigators believe Issaoui travelled to Europe via Italy's Mediterranean island of Lampedusa on September 20.
The 21-year-old arrived at the mainland Italian port of Bari on October 9 before arriving in Nice just two days before the attack.
France is on edge after the republication in early September of cartoons of the Prophet Mohammed by Charlie Hebdo, which was followed by an attack outside its former offices, the beheading of a teacher, and the attack in Nice.
On Saturday, an attacker armed with a sawn-off shotgun shot a Greek Orthodox priest before fleeing in the French city of Lyon.
Nikolaos Kakavelaki, 52, was closing his church when he was attacked and is now in serious condition.
A suspect was initially detained but was released on Sunday after investigators found no evidence he was connected to the shooting.
Prosecutors say they are keeping all hypotheses open but so far have not referred the case to anti-terror colleagues.
French President Emmanuel Macron had vowed after the beheading earlier this month of teacher Samuel Paty, who showed his class a cartoon of the prophet -- that France would never renounce the right to caricature.