At least 84 people have been killed and over 100 injured as a 25-tonne lorry zigzagged through crowds in Nice, France.
The French President has described the Bastille Day tragedy as “undoubtedly a terrorist attack”.
"France was hit on the day of her national holiday, July 14, symbol of liberty, because the rights of man are denied by fanatics and France is inevitably their target," French President François Hollande announced.
Whether the truck driver, who was shot by police, was affiliated with Islamic extremists is currently not known.
He was reportedly a local 31 year-old French-Tunisian with a minor criminal record, although police have yet to confirm his identity. It is not known whether he had any accomplices.
At this stage, no group has claimed responsibility for the attack, although journalists are reporting that several months ago, a spokesman for the so-called Islamic State called for followers to carry out just such an attack
Either way, President Hollande has confirmed that this was a terrorist attack and has extended the state of emergency in France – which was to end in two weeks – for another three months.
The Promenade des Anglais in Nice has been closed indefinitely and several cultural events have been cancelled, including a Rihanna concert and the Nice Jazz Festival.
Gordon Woo, a terrorism expert at risk modelling firm Risk Management Solutions (RMS), said: “The use of vehicles by terrorists is usually associated with the carrying of improvised explosives although there are precedents for them being used to drive into crowds of people, notably in Jerusalem.
“However it is exceptional for the death toll from such an attack to exceed 50. Yesterday’s attack in Nice, France has caused understandable shock at the way so many casualties could be inflicted,” he said.
The targeting of this attack conforms with a basic principle of terrorism risk analysis - that name recognition is a key factor, argued Woo.
“The Promenade des Anglais is to Nice what the Champs Élysées is to Paris,” he said.
“This terrorist attack can also be understood in terms of threat displacement. The French security services were on high alert for terrorist disruption of the Euro 2016 soccer tournament, which concluded on July 10 in Paris.
“Terrorism risk analysis predicts that, if security is very tight around a primary target, an attack will be displaced to another venue and another time,” said Woo at RMS.
This attack is the largest since the Paris attacks in November 2015, which shortly followed attacks in January 2015 when Charlie Hebdo’s office was targeted.
Soon after the January Paris attacks, France unveiled a series of anti-terror policies. Prime Minister Manuel Valls announced more than €700m ($800m) would be spent over the next three years on "the fight against terrorism."
The 2015 attacks by known Islamists exposed weaknesses in French intelligence, and Valls said some 3,000 people with jihadist ties needed to be monitored.
In February 2015, Valls also said that the number of people with links to "terrorist networks" in Syria and Iraq had increased by 130% in the past year.
France will create 2,680 new jobs to fight extremism, just under half of them in the intelligence services, he announced.
Nice municipality, on the French Riviera, hosts over 4m tourists each year, and is the second most important tourist city in France. The city’s tourist office states that Nice accounts for 40% of tourist flows in the French Riviera.