France's president, Francois Hollande, addressed the country early Friday to condemn the attacks.
"It is France as a whole which is threatened by Islamist terrorism. In such circumstances, we must show our absolute vigilance and determination," he said. "France is strong. France will always be stronger than the fanatics who want to strike France today."
As news of the tragedy spread, celebrities, politicians and notable figures around the world expressed their condolences and reflected on the attack.
POLITICIANS AND WORLD LEADERS
"Every American stands in strong solidarity with the people of France" —Hillary on the attack in Nice pic.twitter.com/BBGgHucSE0— Hillary Clinton (@HillaryClinton) July 15, 2016
My prayers and condolences to the victims and families of the terrible tragedy in Nice, France. We are with you in every way!— Donald J. Trump (@realDonaldTrump) July 15, 2016
I pray for the victims of the attack in Nice and their families. I ask God to convert the hearts of the violent blinded by hate.— Pope Francis (@Pontifex) July 15, 2016
British Prime Minister Theresa May
I am shocked and saddened by the horrifying attack in Nice last night. Our hearts go out to the French people: https://t.co/xd0arcO72R— Theresa May (@theresa_may) July 15, 2016
European Council President Donald Tusk
NATO Secretary General Jens Stoltenberg
I am appalled and saddened by the cowardly terrorist attack in Nice. NATO stands in strong solidarity with the people of France.— Jens Stoltenberg (@jensstoltenberg) July 15, 2016
Canadian Prime Minister Justin Trudeau
Canadians are shocked by tonight's attack in Nice. Our sympathy is with the victims, and our solidarity with the French people.— Justin Trudeau (@JustinTrudeau) July 14, 2016
At a Star Wars event in London, host Gwendoline Christie took a moment of silence.
"It's impossible for us to sit here at celebration...without thinking of the terrible events that happened not far from here," the Game of Thrones and The Force Awakens star said. "Our hearts go out to the people in Nice, France."
Rihanna posted on Instagram, "Due to the tragic events in #Nice, my concert scheduled for tomorrow July 15 at Allianz Stadium will not be going ahead as planned. Our thoughts are with the victims and their families."
Pray for Nice. Pray for France. Pray for our world ❤️ my heart is broken— Ariel Winter (@arielwinter1) July 14, 2016
Heartsick over Nice. Horrified.— Lin-Manuel Miranda (@Lin_Manuel) July 14, 2016
To our brothers and sisters in Nice, we stand with you, we pray for you, we mourn for you. #PrayForNice— Josh Gad (@joshgad) July 14, 2016
Devastating news from France... Pain, suffering, fear, loss... All my love to my friends in France. Stay strong 💔❤️ #Nice— regina spektor (@respektor) July 14, 2016
ABC News contributed to this report.