A lorry has struck a crowd in the southern French city of Nice after Bastille Day celebrations, killing at least 80 people, including children, and dozens injured, officials say.
It happened on the famous Promenade Des Anglais after a firework display. The lorry driver was shot dead and guns and grenades were found inside the lorry.
President Francois Hollande said the attack was of a “terrorist nature”.
He has now extended a state of emergency across France by three months.
France had been on the high alert following the last November’s attacks in Paris in which 130 people died and many were wounded.
The state of emergency had been due to end on 26 July.
“France is badly hit,” Mr Hollande said, adding that “we need to do everything we can to fight against” such attacks.
“All of France is under the threat of Islamic terrorism,” he said, adding that “several children” were among those killed.
A reporter for the AFP news agency said this incident took place as the firework display was ending, adding: “We saw people hit and bits of debris flying around.”
Another image on Twitter showed a white lorry stopped in the middle of the promenade with damage to its front, and four police officers observing it while taking cover behind a palm tree.
One eyewitness told BFM TV: “Everyone was calling run, run, run there’s an attack run, run, run. We heard some shots. We thought they were fireworks because it’s the 14th of July.
“There was great panic. We were running too because we didn’t want to stick around and we went into a hotel to get to safety. “