Yellow flowers are laid next to blood stains on the attack scene at the Promenade des Anglais in Nice, France, July 16, 2016. [Photo/Xinhua]

PARIS - French Prime Minister Manuel Valls has cautioned French citizens that they have moved to a different age, saying that "terrorism is now part of our everyday lives for a long period of time."

At least 84 people were killed, and around 300 more injured on Thursday night when a truck crashed into a crowd in the southern city of Nice during France's national day celebrations.

In an interview with the French newspaper Journal Du Dimanche (JDD) published on Sunday, Valls said,"Some irresponsible politicians say that this attack could be avoided. But there is no such thing with zero risk."

"I have always told the truth about terrorism: we are facing a war, there will be further attacks. It is hard to say, but more lives will be lost. It will take a long time,"stressed Valls.

Concerning the questions on the planning and the organization of the Bastille Day firework display in Nice, Valls said, "the investigation will get to the bottom of this. But I do not want unnecessary controversies. The government offices and the city of Nice both planned the Bastille Day celebration, as they did with the Nice Carnival and the UEFA Euro 2016. Three meetings were organized for its preparation."

"64 national police and 42 municipal police officers were deployed for this event, in addition to the normal activities on the rest of the city. If former mayor of Nice Christian Estrosi had the slightest doubt, he could have had the event cancelled. He did not do so," pointed out Valls.

He added: "The Bastille Day terrorist attack is the embodiment of these new operating methods."

"Let me clarify this aspect: right now, it is not possible to tell from the terrorist's background if he was a jihadist. But at the same time, his operating method corresponds point-by-point to the instructions of the Islamic State group: to target a symbolic period (Bastille Day celebration), to cause the largest number of victims, to use any means available (a knife, a car, a truck) to kill innocent people."

Following the Nice attack, three days of national mourning were declared. Meanwhile, the investigation into the attack is going on.