At least 80 people, including many children, have been killed and another 100 wounded after an attacker drove a lorry at high speed into a crowd celebrating Bastille Day in the French Riviera city of Nice.
The lorry careered for hundreds of metres along the Promenade des Anglais seafront late on Thursday, slamming into families and friends after a firework display marking the anniversary of the 1789 revolutionary storming of the Bastille.
Witnesses described a horrific scene, with bodies strewn along the roadway.
"People went down like ninepins," Jacques, who runs Le Queenie restaurant on the seafront, told the France Info radio station.
"It's a scene of horror," Eric Ciotti, a local member of parliament, told the station, saying the truck "mowed down several hundred people".
In a pre-dawn address to the nation, French President Francois Hollande said "France is filled with sadness by this new tragedy".
Hollande said he had no doubt the attack was an act of "terrorism", calling it an assault on liberty by fanatics who despised human rights.