The attacker, identified by a police source as a 31-year-old Tunisian-born Frenchman, also opened fire before police shot him dead. He had been known to the police for common crimes but not to the intelligence services, the source said.

Interior Minister Bernard Cazeneuve said 18 of the injured  were in a critical condition after the 25-tonne truck zigzagged along the seafront Promenade des Anglais as a fireworks display marking the French national day ended just after 10:30 p.m. (2030 GMT).

The attack, which came eight months and a day after Islamic State gunmen and suicide bombers struck Paris on a festive Friday evening, seemed so far to be the work of a lone assailant.

Hollande said in a pre-dawn address that he was calling up military and police reservists to relieve forces worn out by a state of emergency begun after the militant group killed 130 people in the French capital in November.
In pics: Deadly terror strike mows down 80 in France
Only hours earlier Hollande had announced the state of emergency would be lifted by the end of July, but the president said that following the attack, in which several children were killed, it would now be extended by a further three months.

"France is filled with sadness by this new tragedy," he said. Officials said hundreds were hurt as the driver wove along the seafront, knocking them down "like skittles". A local government official said weapons and grenades were found inside the unmarked articulated truck.

Dawn broke on Friday with the pavements smeared by dried blood, while smashed children's strollers, an uneaten baguette and other debris were strewn about the Mediterranean seaside promenade. Small areas were screened off at regular intervals. What appeared to be bodies covered in blankets were visible through the gaps.

The scene appeared to confirm what one city official said during the night - that the truck drove a full 2 km (1.5 miles)along the promenade after mounting the kerb.

The truck, a rental vehicle according to local officials, was still were it came to rest, its windscreen riddled with bullets. Hollande called the tragedy on the day that France marks the 1789 revolutionary storming of the Bastille prison in Paris as an attack on liberty by fanatics who despised human rights.

France would, nonetheless, continue its air operations against Islamic States in Syria and Iraq. Police were trying to establish whether the driver might have had any accomplices in a city with a reputation for Islamist activism. There had been no claim of responsibility this morning.

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