The toll of the terrorist attack on a Bastille Day fireworks celebration in the southern French city of Nice has risen to 84 dead and 202 injured, as the government identified the attacker as a 31-year-old native of Tunisia, extended a national state of emergency and absorbed the shock of a third major terrorist attack in 19 months.

The Paris prosecutor, Francois Molins, identified the attacker as Mohamed Lahouaiej Bouhlel, 31, a delivery-truck driver who was born in 1985, and raised in Msaken, a town in northeastern Tunisia. Police searched two locations in Nice on Friday, local time, including a home with Bouhlel's name outside it. Mr Molins confirmed that the ex-wife of the suspect, has been arrested and is being held by police.

"We will not give in to the terrorist threat," Prime Minister Manuel Valls said Friday morning after a Cabinet meeting led by President Francois Hollande. "The times have changed, and France is going to have to live with terrorism."

The first images of Bouhlel, from what purported to be his 'carte de sejour' or French residency visa, were published in French and other European media outlets.

No organised group has claimed responsibility for the attack, although online accounts associated with the Islamic State and al-Qaida have cheered it.

The attack unfolded Thursday around 10:30 pm local time, when a large truck turned left onto the Promenade des Anglais, a seaside boulevard filled with an enormous crowd of spectators. The truck initially killed two people, and continued for around two kilometres down the boulevard, brutally mowing down people left and right until police officers shot and killed Bouhlel outside a hotel and casino.

Ten children among the dead

The 84 dead included 10 children and teenagers, Mr Molins said. Among the victims were two German students and their teacher, two Americans, two Tunisians and one Russian. Of the 202 people wounded, 52 had serious injuries and 25 were in intensive care, Mr Molins said.

Brodie Copeland, 11, and his father Sean 51, from Lakeway, a city in the Texas Hill Country outside Austin, were among the first victims identified.

Officials cancelled festivities in Nice, a seaside city of 340,000, including a five-day jazz festival and a concert on Friday night by Rihanna.

"There are many children, young children who had come to watch fireworks with their family, to have joy, to share happiness, delight, amazement, and who were struck, struck to death, merely to satisfy the cruelty of an individual, and maybe of a group," Mr Hollande said, flanked by Mr Valls and Health Minister Marisol Touraine, after meeting with victims and medical workers at the Pasteur Hospital in Nice.

Mr Hollande said the victims he had met were physically and psychologically scarred. "Many told me that they had no recollection of what might have caused their wounds," he said. "However, they remember the bodies that were torn to shreds right in front of their eyes."

Attacker not known to intelligence agencies

While he had several run-ins with the law previously, Bouhlel, a 31-year-old Nice resident born in Tunisia, was not on a watch list of French intelligence services as a suspected militant. Described by his neighbours as a handsome but frightening man, Bouhlel, was convicted only once before: for road rage.

He was convicted for the first time in March this year, French Justice Minister Jean-Jacques Urvoas said.

"There was an altercation between him and another driver and he hurled a wooden pallet at the man," Urvoas said.

As it was his first conviction, Bouhlel was given a suspended sentence and had to contact police once a week, which he did.

Tunisian security sources told Reuters Bouhlel had last visited his hometown of Msaken four years ago.

​"He is totally unknown to the intelligence services, both locally and nationally," Mr Molins said, and he had never appeared in any terrorism-related government database.

'One of the most beautiful cities on the planet'

Despite mounting criticism about France's ability to prevent terrorism attacks, Mr Hollande praised French security forces, saying they had "taken all necessary measures so that this fireworks show might be as protected as possible, as had been the case during the European Championship soccer tournament."

"Why Nice?" Mr Hollande asked.

"Because it is a city that is known worldwide, one of the most beautiful cities on the planet," Mr Hollande said. "Why on the 14th of July? Because it is a celebration of freedom. It was, therefore, indeed to affect France that the individual committed this terrorist attack."

Hours before the attack Thursday, Mr Hollande had said that a state of emergency put in place after the November 13 attacks in and around Paris would end soon. The government will now seek to extend the state of emergency for three months.

As France announced three days of national mourning, starting Saturday, world leaders from Pope Francis and President Barack Obama to Chancellor Angela Merkel of Germany and Britain's new prime minister, Theresa May expressed sympathy and outrage.

Witnesses describe horrific scene

Along with the adequacy of terrorism prevention, the use of a large commercial truck as the principal weapon raised new questions about how to prevent such attacks.

Graphic television and video images showed the truck accelerating and tearing through the crowd, dozens of victims sprawled in its path, and the bullet-riddled windshield of the vehicle. Municipal officials and police officers initially described the truck as having been full of weapons and grenades, but those accounts had not been verified.

One witness, Raja el-Kamel, 43, said the attack seemed, at first, as if it might have been the act of a drunken driver.

"There was a white truck that was advancing slowly," Ms Kamel, 43, said. "Then it started to plow into the crowd, zigzagging and crushing people. I could not believe it."

"But then I saw him aiming at people and crushing them," she said.

She added: "I was looking on my right, and there were bodies on the ground. I was looking on my left, there were also many bodies on the ground. It was a massacre."

No group claims responsibility

The Islamic State, the militant group that asserted responsibility for the attacks in Paris, did not make any immediate claims for the Nice assault. The Islamic State's Amaq News channel on the Telegram instant-messaging service had no mention of the assault.

However, numerous social media accounts linked to the Islamic State and to al-Qaeda - which are competitors in the global jihadi struggle - praised the rampage. One pro-al-Qaeda channel quoted Mr Valls expressing pain, followed by an emoji of a person laughing and of two hands clapping.

The New York Times, Reuters, Washington Post, Fairfax Media