President Barack Obama on Thursday condemned the deadly attack in Nice and offered any assistance France needed to investigate.
"On behalf of the American people, I condemn in the strongest terms what appears to be a horrific terrorist attack in Nice, France, which killed and wounded dozens of innocent civilians," Obama said in a statement.
US secretary of state John Kerry, who had been in Paris earlier in the day for a Bastille Day parade, said: "The United States will continue to stand firmly with the French people during this time of tragedy. We will provide whatever support is needed."
At least 77 people were killed and scores injured when a truck slammed into a crowd in the French Riviera city during Bastille Day celebrations.
According to the Downing Street, the British Prime Minister Theresa May is being briefed on the "terrible incident" and the UK authorities stand ready to assist their French counterparts.
"We are shocked and concerned by the scenes there. Our thoughts are with all those affected by this terrible incident on what was a day of national celebration." a Downing Street spokesman said, "We stand ready to help any British nationals and to support our French partners."
May, who became prime minister on Wednesday after six years as Britain's interior minister, was due to head to Scotland later Friday for talks on the Brexit vote fall-out.
A foreign office spokesman said that they are in touch with the local authorities and are seeking more information.
"If you are in the area, follow the instructions of the French authorities," he added, in a message to British citizens.
French local government official Sebastien Humbert told BFMTV that the driver of the truck was shot dead after barrelling down Nice`s palm-lined Promenade des Anglais in what he called "a major criminal attack".
Witness Roy Calley, who said he lived 200 metres from the promenade, told the BBC there was "all hell breaking loose" and the situation was "pretty horrendous".
"It was a celebratory atmosphere, it was fun, people were enjoying themselves. Suddenly I heard a huge, what I can only describe as maybe an explosion or a crash. A lot of people were screaming. That was followed by what I thought were maybe gunshots."
Canadian Prime Minister Justin Trudeau on Thursday also pledged his support to France .
"Canadians are shocked by tonight’s attack in Nice. Our sympathy is with the victims and our solidarity with the French people," Trudeau said on Twitter.
Canadian opposition leader Thomas Mulcair, head of the New Democratic Party and a French citizen by marriage also offered his condolences ,"We stand with those injured and the families of the many killed,"
Leaders gathering for the first session of the 2016 Asia-Europe Meeting (ASEM) stood for a moment of silence on Friday.
"All the participants of the 11th ASEM summit, we are together with the people of France and the people of Europe. I think it's appropriate to begin our session with one minute silence," said Mongolian President Tsakhiagiin Elbegdorj.
While the United Nations Security Council called the attack "barbaric and cowardly", European Council President Donald Tusk called it "a sad day for France, for Europe". He said it was "tragic" that "the subjects of the attack were people celebrating liberty, equality and fraternity."
Chinese Premier Li Keqiang offered his "condolences" to the victims and said China opposed all forms of terrorism.
Indian Prime Minister Narendra Modi condemnerd the attack in a series of tweets.
"Appalled by the horrific attack in Nice. I strongly condemn such mindless acts of violence. My thoughts are with the families of deceased" he tweeted. " I hope the injured recover soon. India shares the pain & stands firmly with our French sisters & brothers in this hour of immense sadness."