An attacker killed at least 80 people and injured scores more when he drove a truck at high speed into a crowd celebrating Bastille Day in the French Riviera city of Nice late on July 14.
French authorities said police shot and killed the driver, who drove the heavy, long-distance truck for about 2 kilometers into the mass of spectators leaving a fireworks display along the famed Promenade des Anglais seafront.
The man had opened fire on the crowd, Nice Mayor Christian Estrosi said weapons and grenades were found inside the truck after he was killed. Several of the victims reportedly died of gunshot wounds.
"It's the most terrible tragedy in our city's history. Over 70 people died," Estrosi wrote on Twitter.
"It's a scene of horror," local member of parliament Eric Ciotti told France Info, saying the truck "mowed down several hundred people" before being stopped by police.
Officials later said the death toll had risen to 84, with dozens to hundreds of others wounded. Hours after the attack, dozens of bodies lay on the ground covered in white sheets.
The Paris Prosecutor's Office opened a terrorism investigation into the attack. The driver has not yet been identified and no group has claimed responsibility. There was no sign of any other attack, though residents of the city were advised to stay indoors.
French President Francois Hollande said the attack was clearly a "terrorist" act, the third on French soil in 18 months.
"France is horrified by what has happened, this monstrosity which is using a truck to deliberately kill dozens of people," he said in an early morning televised address to the nation on July 15.
France "will always be stronger, I promise you, than the fanatics that want to strike it," he said."Nothing will make us yield in our will to fight terrorism. We will further strengthen our actions in Iraq and in Syria. We will continue striking those who attack us on our own soil," he said, alluding to the Islamic State group.
He said he will convene a security cabinet meeting early on July 15.
U.S. President Barack Obama condemned "what appears to be a horrific terrorist attack," and said "we stand in solidarity and partnership with France, our oldest ally, as they respond to and recover from this attack."
The United Nations Security Council in a statement strongly condemned the "barbaric and cowardly terrorist attack," which it called "criminal and unjustifiable."
European Council President Donald Tusk said Europe "will stand united with the families of victims, the French people, and the government in the fight against violence and hatred."
German Chancellor Angela Merkel, speaking on the sidelines of a summit of Asian and European leaders in Mongolia, said "Germany stands in the fight against terrorism at France’s side, united with many, many others."
A spokesperson for British Prime Minister Theresa May called the Nice attack "terrible" and said “we are shocked and concerned.”
Chinese Prime Minister Li Keqiang expressed condolences and said "we strongly condemn terrorism in all forms."
Newly appointed British Foreign Secretary Boris Johnson said he was “shocked and saddened” by the loss of life in France.
Eight months ago, Islamic State militants killed 130 people in Paris in the worst of several terrorist attacks in France and Belgium in the past two years.
But more recently, no major incidents had marred the month-long Euro 2016 soccer tournament in France despite fears of an attack on the international crowds that attended those games.
Vehicle attacks have been used by isolated members of militant groups in recent years, notably in Israel, though never to such devastating effect.
France had mobilized extra security for the national day of celebration commemorating the storming of the Bastille prison in 1789. Approximately 11,500 security personnel were on hand for the traditional military parade in Paris.
With reporting by AFP, Reuters, AP, dpa, and BFM TV