At least 84 people have died, including children, after a lorry slammed through a crowd celebrating Bastille Day in the southern French city of Nice.
The driver ploughed on for 2km on the Promenade des Anglais after fireworks, before being shot dead by police.
Security forces and ambulances raced to the scene, and authorities from the local Alpes-Maritimes prefecture urged residents to stay indoors.
One eyewitness reported seeing the driver slam the lorry into revellers celebrating Bastille Day on the city’s famous Promenade des Anglais.
He then emerged from the vehicle and started shooting, local resident Wassim Bouhlel told news agency.
“There was carnage on the road, dead bodies everywhere.”
France had been on high alert since those attacks on Paris in November in which 130 people died and hundreds were wounded.
French President Condemns Bastille Day terror Attack
French President, Francois Hollande said the attack was of “an undeniable terrorist nature”.
Mr Hollande said:
“France is badly hit. We need to do everything we can to fight against such attacks.”
“All of France is under the threat of Islamic terrorism.”
Several children were among the dead revellers killed by the truck driver.
A state of emergency has been in place since November’s Paris attacks. This has been extended by three months.
The BBC reports that shots were exchanged between the police and the occupants of the lorry.
No group has so far claimed responsibility, however, prosecutors said the inquiry would be handled by anti-terror investigators.
Some reports spoke of shots being exchanged between police and the occupants of the lorry but these have not been confirmed.
A video on twitter showed people running through the streets in panic following the incident.
A journalist with the Nice Matin newspaper reported from the scene that there was “a lot of blood and without doubt many injured”.