The driver of the truck was shot dead after barrelling two kilometres through the crowd on the palm-lined Promenade des Anglais, sending hundreds fleeing in terror and leaving the area strewn with bodies.
“An individual drove a truck into the crowd. He was killed by police,” said interior ministry spokesman Pierre-Henry Brandet.
The bloodshed came on Bastille Day, a celebration of everything France holds dear, its secular republic and the values of “Liberte, Egalite, Fraternite” (Freedom, Equality, Fraternity).
It was after a day of military pomp and ceremony in Paris – where armed forces, tanks and fighter jets swooped down the Champs Elysees avenue – and spectacular firework displays that the crowd of revellers in Nice was attacked.
A photograph showed the front of the truck riddled with bullet holes and badly damaged, with burst tyres, while a lone doll lay abandoned on the promenade where families celebrated the holiday just hours earlier.
Robert Holloway, an AFP reporter who witnessed the white truck driving at speed onto the seaside road, described scenes of “absolute chaos”.
“We saw people hit and bits of debris flying around. I had to protect my face from flying debris,” he said.
The president of the region, Christian Estrosi, said 77 people were killed, while many others were reported to be in a “critical” condition.
Estrosi said the truck contained “guns” and “larger weapons”.
'Horrific terrorist attack'
US President Barack Obama condemned “what appears to be a horrific terrorist attack”, although no group had claimed responsibility for the incident.
If confirmed as a terror attack, it would be the third major strike against France in less than 18 months and prosecutors said anti-terrorist investigators would handle the probe.
“Investigations are currently under way to establish if the individual acted alone or if he had accomplices who might have fled,” the interior ministry spokesman said.
President Francois Hollande expressed his “support and solidarity” with the residents of Nice, and was due to chair a meeting of the country’s defence and security chiefs on Friday (July 15).
The bloodshed comes eight months after Islamic State jihadist attacks on Paris nightspots left 130 people dead, dealing a hard blow to tourism in one of the world’s top destinations.
France has been under a state of emergency ever since the November 13 Paris attacks, which came after 17 were killed in another attack in January at various sites such as the Charlie Hebdo magazine and a Jewish supermarket.
The Islamic State group has repeatedly singled out France as a prime target for its military actions against the group in Iraq and Syria, and hundreds of jihadists have left France to go and fight in their ranks.
‘People were tripping over’
The Mediterranean city of Nice, with its pebble beaches and clear blue water, has been a magnet for sun-seekers and the jet-set since the 19th century.
A concert by popstar Rihanna due Friday was cancelled in the wake of the attack, as well as the Nice Jazz festival.
An Australian citizen, Emily Watkins, who was caught up in the chaos told the Australian Broadcasting Corporation that while she saw the truck, she did not realise what had happened.
“There was a lot of screams coming from ahead of us where the truck was… People were tripping over and trying to get into hotel lobbies and restaurants or car parks or anywhere they could to get away from the street.”
The Promenade des Anglais was sealed off, crawling with police and ambulances as authorities from the local Alpes-Maritimes prefecture urged residents to stay indoors.
Over the past week, France had been breathing a sigh of relief after successfully hosting the month-long Euro 2016 football championship, which passed off without incident despite fears of attacks.
The tournament brought an all-too-brief burst of joy to a gloomy France, bogged down after the two attacks in 2015, violent anti-government protests, strikes and floods.
The attack sent shockwaves across the globe with China offering “condolences” and US Republican presidential hopeful Donald Trump postponing the announcement of his pick for running mate because of the attack.
European Council President Donald Tusk said: “It’s a sad day for France, for Europe, for all of us.”
“The subjects of the attack were people celebrating liberty, equality and fraternity.”