Update 6.20pm: A Rihanna concert scheduled for Friday night at the Allianz Riviera stadium in Nice has been cancelled, as have the city's jazz festival, which was due to run from Saturday to Wednesday, and some of the Bastille celebrations over the weekend.
Update 5.10pm: More than 200 people were wounded and 84 killed after a 31-year-old French-Tunisian drove a truck through crowds celebrating Bastille Day in Nice.
A French prosecutor said that of the 202 people injured, 25 are on life support and 52 in a critical condition as he confirmed the attack was carried out by Mohamed Lahouaiej Bouhlel, who lived in Nice.
French president Francois Hollande and prime minister Manuel Valls visited the city before three days of national mourning begin on Saturday.
They have extended the country's nine-month-old state of emergency and vowed to deploy thousands of police reservists on the streets after the massacre of pedestrians leaving a fireworks display for France's national independence day.
Update 3.50pm: The suspected attacker in the Nice lorry massacre was a father-of-three known to police for domestic violence, it has been claimed.
The driver was named in reports as Mohamed Lahouaiej Bouhlel, a 31-year-old from Nice with French-Tunisian nationality.
Local media said he was identified from an ID card found inside the vehicle following the massacre.
A search was launched of his former home on Friday morning, as well as his former marital home. He was said to have separated in 2012.
Bouhlel was known to police for delinquency and domestic violence, but not on a list of radicalised people, according to the Nice-Matin newspaper.
He was reported to have hired the vehicle last Monday, taking the biggest from a fleet of lorries - a 19 tonne truck normally used for removals.
Neighbours described him as withdrawn, saying he was "alone" and "silent".
Scores of people including several children died after the vehicle drove through crowds celebrating Bastille Day in the city in the south of France.
Eyewitnesses said the driver swerved from side to side as he drove for hundreds of metres along the famous Promenade des Anglais on the seafront, before he was shot dead by police.
Update 3.20pm: A hospital treating children injured in last night's terror attack in Nice has said it has been unable to find some of their parents.
Fifty youngsters are being cared for after a lorry was driven at a crowd watching fireworks for Bastille Day.
The Lord Mayor of Dublin has offered his condolences to the people of France and a book of condolences has been opened in Dublin for people to sign.
Update 2.30pm: An American father and son are among those killed in the terror attack in Nice.
Sean Copeland, 51, and his 11-year-old son Brodie from Texas were on holiday when the atrocity took place.
In a statement, the Copeland family said: "We are heartbroken and in shock over the loss of Brodie Copeland, an amazing son and brother who lit up our lives, and Sean Copeland, a wonderful husband and father. They are so loved."
Hill Country Baseball, believed to be a local sports club, wrote on Facebook: "This evening we would like to ask that the HC family keep the Copelands in your prayers.
"This afternoon our very own Brodie Copeland, as well as his father Sean Copeland, were killed during the terrorist attack in Nice, France…
"You are in our hearts, thoughts, and prayers. Rest in peace, Brodie and Sean, you will be remembered by many."
Another person believed to be a victim is a Russian, named in reports as 21-year-old student Victoria Savchenko.
Update 1.30pm: Security have allowed passengers back inside Nice Airport after evacuating the building earlier this afternoon.
A statement on the airport website read: "Despite the dreadful events that occured, access to the airport and Air traffic won’t be disrupted."
Passengers allowed back into Nice airport. Situation seems to be back to normal #cbc— Thomas Daigle (@thomasdaigle) July 15, 2016
BREAKING: AP reporter says passengers evacuated from Nice airport are being allowed to return, pick up their luggage.— The Associated Press (@AP) July 15, 2016
Update 1.08pm: Nice Airport is being evacuated after an unattended bag was found, it has been reported. More as we get it.
Update 12.41pm: The Department of Foreign Affairs has issued a statement following reports of that Irish citizen has been seriously injured in last night’s attacks in Nice.
“The Department of Foreign Affairs and the Irish Embassy in France are following up on all concerns which have been expressed to them as to the welfare of Irish citizens who may have been in the Nice area yesterday evening,” the statement read.
“The Embassy is in ongoing contact with the French authorities. We have particular concerns for the welfare of one Irish citizen, which we are following up urgently.
“We will provide an update on the situation in due course.”
Update 11.35am: There are unconfirmed reports that an Irish citizen was injured and in a critical condition in the attack. More as we get it.
Update 10.48am: The children's hospital in Nice said it has treated about 50 youngsters injured in the terror attack in Nice in which at least 84 people were killed, including two who died during or after surgery.
Stephanie Simpson, the communications director for the Lenval foundation hospital, said that injuries included fractures and head injuries and that the victims were aged 18 or under.
She said: "Some are still life-and-death."
Update - at least 50 children aged 18 or under have been treated in hospital including two who died during or after surgery #NiceFrance— Sky News Breaking (@SkyNewsBreak) July 15, 2016
France has declared three days of national mourning, beginning tomorrow.
French Prime Minister Manuel Valls also confirmed that a measure extending the country's state of emergency would go before politicians next week.
Update 10am: Christian Estrosi, the regional president in Nice, said some of the city's 1,200 security cameras had pinpointed the moment the attacker boarded the truck, far from the seaside "in the hills of Nice" and could follow his path to the promenade.
Mr Estrosi called for the investigation to focus on any accomplices.
"Attacks aren't prepared alone. Attacks are prepared with accomplices," he said. "There is a chain of complicity. I expect it to be unveiled, discovered and kept up to date."
Mr Estrosi said more than 10 children were among the dead and he said France needed to think carefully about its next response to attacks, as previous responses were not enough to protect the people.
Update 8.36am: A politician for the region that includes Nice has given new details of the horrifying last minutes of the attack which left 84 dead.
"A person jumped on to the truck to try to stop it," Eric Ciotti told Europe 1 radio.
"It's at that moment that the police were able to neutralise this terrorist. I won't forget the look of this policewoman who intercepted the killer."
He also said that some people on the Riviera city's famed waterfront promenade tried to escape into the water.
The truck ploughed into the crowd over a distance of two kilometres (about 1.2 miles), he said, and broadcast footage showed a scene of horror up and down the promenade, with bodies on the floor, some piled near one another and others bleeding on to the road.
Interior minister Bernard Cazeneuve, who travelled to the scene, said police were trying to identify the driver.
Mr Ciotti said identification papers were found in the truck and that investigators were trying to determine whether they were legitimate.
Update 8.20am: The death toll from last night’s attack in Nice rose to 84 from 80 this morning.
The number is expected to rise further, as it is understood that 14 people, many of them children, are in critical condition in hospital.
A lorry loaded with weapons and hand grenades drove on to a pavement for more than a mile, ploughing through Bastille Day revellers in the French resort city of Nice and killing at least 84 people before police shot dead the driver.
Nice prosecutor Jean-Michel Pretre described a horrific scene, with bodies strewn along the road, and Sylvie Toffin, a press officer with the local authority, said the lorry ran over people on a "long trip" down the pavement near Nice's beachfront Palais de la Mediterranee.
Wassim Bouhlel, a Nice native, said he saw the lorry drive into the crowd.
"There was carnage on the road," he said. "Bodies everywhere." He said the driver emerged with a gun and started shooting.
France's interior minister Bernard Cazeneuve said 80 people were killed, including children, and 18 were in a critical condition.
The Paris prosecutor's office announced an investigation for "murder, attempted murder in an organised group linked to a terrorist enterprise".
"We are in a war with terrorists who want to strike us at any price and in a very violent way," Mr Cazeneuve said.
Eric Ciotti, the top politician of the Alpes-Maritime department that includes Nice, said the lorry hit the crowd, which had gathered to watch fireworks, over a distance of 1.2 miles. Many of those on the ground were in shorts and other summer clothing.
Mr Ciotti told BFM TV that police killed the driver "apparently after an exchange of gunfire".
The president of the Provence Alpes Cote d'Azur regional council, which includes Nice, said the vehicle was loaded with arms and grenades.
Christian Estrosi told BFM TV that "the driver fired on the crowd, according to the police who killed him"
Images broadcast across French media showed revellers running for their lives down Nice's palm tree-lined Promenade des Anglais, the famous seaside boulevard named for the English aristocrats who proposed its construction in the 19th century.
Video footage showed men and women - one or two pushing strollers - racing to get away from the scenes. And, in what appeared to be evidence of a gun battle, photos showed a lorry with at least half a dozen bullet holes punched through its windscreen.
It was not immediately clear who would have been behind an attack, but France has recently seen a spate of dramatic assaults by jihadist groups, including the Islamic State which straddles Iraq and Syria.
President Francois Hollande said in a televised statement that all of France was under an "Islamist terrorist threat" and extended by three months a state of emergency that has been in place since the November attacks that killed 130 in Paris was to end on July 26. The decision needs parliamentary approval.
"The terrorist character (of the attack) cannot be denied," he said.
Mr Hollande said he was calling a defence council meeting on Friday then heading to Nice. He listed several measures to bolster security in France after two waves of attacks last year that killed 147 people.
Besides continuation of the state of emergency and the Sentinel operation with 10,000 soldiers on patrol, he said he was calling up "operational reserves", those who have served in the past and will be brought in to help police, particularly at French borders.
US president Barack Obama condemned what he said "appears to be a horrific terrorist attack" and European Council president Donald Tusk said it was a "tragic paradox" that the victims of the attack in Nice were celebrating "liberty, equality and fraternity" - France's motto - on the country's national day.
Writing online, Nice Matin journalist Damien Allemand ,who was at the waterside, said the fireworks display had finished and the crowd had got up to leave when they heard a noise and cries.
"A fraction of a second later, an enormous white truck came along at a crazy speed, turning the wheel to mow down the maximum number of people," he said.
"I saw bodies flying like bowling pins along its route. Heard noises, cries that I will never forget."
Graphic footage showed a scene of horror up and down the Promenade, with broken bodies splayed out on the asphalt, some of them piled near one another, others bleeding out on to the roadway or twisted into unnatural shapes.
"Help my mother, please!" one person yells out amid a cacophony of screaming and crying. A pink girl's bicycle is briefly seen overturned by the side of the road.
The origin and authenticity of the footage could not immediately be verified.
Kayla Repan, of Boca Raton, Florida, was among the hundreds gathered on the promenade to watch fireworks.
"The whole city was running. I got extremely frightened and ran away from the promenade," she said. "It was chaos."