President Francois Hollande has return to Paris for a crisis meeting as reports emerged of a major suspected terror attack on crowds celebrating Bastille Day on the seafront in Nice.
At least 60 people have been killed and many more injured after a truck ploughed into people who had assembled to watch fireworks. The driver of the truck has died in a shootout with police.
Mr Hollande was on holiday in the south-east of France near Avignon. He is heading back to the Interior Ministry Crisis Center in the capital, where he will orchestrate the government's response through the night.
Theresa May, the new British Prime Minister, has been briefed on the events, and the UK Foreign Office tweeted: "We are in touch with the local authorities following the concerning incident in #Nice and stand ready to help any British nationals."
The US President Barack Obama has also been briefed, and the presidential candidate Donald Trump has cancelled a campaign event in light of the events.
The former French President, Nicolas Sarkozy, expressed on Twitter his “deep emotion” over the incident.
"Profound emotion and infinite sadness in light of the attack in Nice," he wrote. "Solidarity to the residents of Nice and Alpes-Maritimes."
And the mayor of Paris, Anne Hidalgo, tweeted: "On behalf of Parisians, all our support and fraternity to the people of Nice. Our cities are united."
