How did the attack unfold?
The white 19-tonne truck plunged into the crowd at around 11.00pm on Thursday night as hundreds of people were on Nice's beachfront Promenade des Anglais to watch the fireworks for France's national day.
Christian Estrosi, head of the local region, said the driver had fired a pistol several times before being shot dead by police.
A photograph showed the front of the truck riddled with bullet holes and badly damaged, with burst tyres.
Interior minister Bernard Cazeneuve told reporters the revellers were killed after the truck ploughed two kilometres (1.3 miles) through the crowd, who had just finished watching the firework show.
A source close to the investigation added an "inactive" grenade was found inside the vehicle, as well as "several fake rifles".
Who is the driver?
The driver of the truck has been formally identified, police sources said on Friday.
He is a 31-year-old Tunisian Mohamed Lahouaiej-Bouhlel, whose identity papers were found in the vehicle after the attack.
Police said he lived in Nice. Other sources said previously he was already known to police for minor criminal offences.
Police investigators and forensic experts entered his apartment around 9.30am with an armed police intervention unit in support, and brought out bags of material later.
Who are the victims?
A local hospital official said that at least two children were among the dead and around 50 had been admitted to hospital, some of whom were fighting for their lives.
Two of the dead were American citizens, a state department spokesman said.
State of emergency extended
France President François Hollande announced he would extend France's state of emergency for three months in the wake of this latest attack and "step up" the government's action against jihadists in Syria and Iraq.
He also called up army reservists to bolster the country's security services that are stretched to the limit.
Prime Minister Manuel Valls also announced three days of national mourning from Saturday 16 July.
The attack is the third major strike against France in less than 18 months and prosecutors said anti-terrorist investigators would handle the probe.
Jihadists have repeatedly singled out France as a prime target for its military actions in Iraq and Syria.
Eiffel Tower to be lit in French tricolour
The Eiffel Tower will be lit in France's national colours from Friday in tribute to the victims of the Nice truck attack, Paris city hall said.
“The mayor of Paris, Anne Hidalgo, has decided to illuminate the Eiffel Tower in red, white and blue tonight and during the (three-day) period of national mourning,” it said in a statement, adding that the illumination would start each night at 10.30pm.
French Prime Minister Manuel Valls earlier said flags would be flown at half-mast from Friday, and three days of national mourning would begin on Saturday.
He also said the government intended to extend the state of emergency, which has been in place since the November 13 terror attacks on Paris, until October.
The National Assembly, France's lower house of parliament, said that it too will also be lit in the national colours.
‘Suspect unknown to intelligence services’
The man who rammed a truck into a crowd at a Bastille Day fireworks display in Nice, killing 84, was "totally unknown" to intelligence services, a top French prosecutor said Friday.
Mohamed Lahouaiej-Bouhlel was "totally unknown to intelligence services... and was never flagged for signs of radicalisation," said anti-terrorism prosecutor Francois Molins.
He also said that the attack was in line with jihadist calls to action.
Visit France to defy terrorists, says UN tourism boss
The UN tourism chief on Friday urged holiday makers to express solidarity with France by visiting the country to defy “terrorists”.
The World Tourism Organisation's Secretary-General Taleb Refai made the call after the deadly Bastille Day assault that left dozens dead, including children, and injured scores of others.
“This is the time to go visit France,” Refai told reporters in Sri Lanka.
- with AFP