More than 70 people are reported dead after a lorry attack on a Bastille Day celebration in Nice.
Chaos erupted on the streets of the Mediterranean city on Thursday night after the lorry ploughed into crowds who had gathered to celebrate the French national day.
Nice regional president Christian Estrosi, who was at the celebration when the carnage happened, said: "This is the worst Nice drama of history for more than 70 victims have already reported.
"We are terrified and we want to present to all the families our sincere condolences.
Bastille Day is France's national day, marking the start of the revolution in 1798 when the prison of the same name was stormed by protesters against the autocratic rule of King Louis XVI.
Colin Srivastava told BBC News: "We were basically sitting just in front of the Old Town in Nice and saw several hundred people running towards us looking panic stricken.
"We tried to ask a few of them what the hell was going on and finally got one that said, 'You need to go, the police have told us to run'.
"Just around about the base of the hill where the castle is in Nice the police came running along and said, 'Run now'.
"We had absolutely no idea what was going on, to be honest with you.
"When we got down into the port in Nice we were told by a few people who'd obviously run faster than we had that there was the story of a lorry that had gone into the people, basically cannoned into the crowd, and there were also shots fired, which is something we didn't hear about until just now on French news."
Former French President Nicolas Sarkozy tweeted: "Deep emotion and infinite sadness at the Nice attack. Solidarity with the Niçois and the inhabitants of the Alpes-Maritimes."