PARIS -- French President François Hollande says "the terrorist character" of the Bastille Day truck attack in Nice cannot be denied.

France's Interior Minister Bernard Cazeneuve said 80 people were killed, including children, and 18 were in critical condition, after a truck drove through the crowds who had just watched a fireworks display on seafront in the city.

The Paris prosecutor's office announced an investigation for "murder, attempted murder in an organized group linked to a terrorist enterprise."

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"We are in a war with terrorists who want to strike us at any price and in a very violent way," Cazeneuve said.

In an nationally televised address hours after the attack, Hollande said the intention of the truck's driver was "killing, crushing and massacring."

"This attack that has all the elements to be called a terrorist attack is once again of an incredible violence and it is clear we have to do everything in our power to fight this terrorist plague," Hollande said.

Just hours after announcing in the traditional Bastille Day interview that the state of emergency, in place since November attacks that killed 130 in Paris, was to be removed, Hollande said it must be extended for three months.

That decision will need parliamentary approval. He also said other measures will be put in place to counter the threat.

Hollande says he will call a defense council meeting Friday that brings together defense, interior and other key ministers, before heading to Nice.

Besides ensuring continuation of the state of emergency and the Sentinel operation that puts 10,000 soldiers on patrol, he said he was calling up reserve to help police, particularly at French borders.

On Twitter, he wrote in French that France is sorrowful, but strong.

La France est éplorée, affligée, mais elle est forte et le sera toujours plus que les fanatiques qui veulent aujourd'hui la frapper. #Nice — François Hollande (@fhollande) July 15, 2016

A truck drove on to the sidewalk and plowed through a crowd of Bastille Day revelers who'd gathered to watch fireworks in the French resort city of Nice late Thursday in what some officials and eyewitnesses described as a deliberate attack.

French network BFM TV said the victims were pedestrians on the famed Promenade des Anglais along the Nice waterfront.

Sylvie Toffin, a press officer with the local prefecture, said the truck "hit several people on a long trip" down the sidewalk near Nice's Palais de la Méditerranee, a building which fronts the beach. Some estimates say the truck went over a mile through the crowd before being stopped.

Toffin confirmed the incident was deliberate, saying, "It's an attack."

The Paris prosecutor's office said it had open a terrorism investigation into the crash.

Almost exactly eight months ago, ISIS militants killed 130 people in a series of attacks in Paris.

The mayor of Nice, Christian Estrosi, said the truck was loaded with arms and grenades, and that the driver was shot dead by police.

"The driver fired on the crowd, according to the police who killed him," Estrosi told BFM TV.

Estrosi said the driver appeared to have "completely premeditated behavior." He added that "the truck was loaded with arms, loaded with grenades."