At least 80 people have died and another 18 are in a state of extreme gravity after the attack by the driver of a truck that rammed the crowd in Nice, said the deputy from the Alpes Maritimes, Eric Ciotti, told the channel "BFM TV".
The multiple homicide occurred on the Promenade des Anglais, the seaside promenade of this resort town on the French Riviera in the Mediterranean, crowded by the start of the summer holiday period and the holiday, on Thursday, the anniversary of the French Revolution.
"We saw wounded people (many victims heard screaming) related an AFP reporter at the site. "It was chaos," he added.
The truck ran over the crowd along a vast sector, which explains the extremely bloody balance, "said the sub-prefect of the region.
The head also noted that "there was an exchange of fire and the driver was killed."
Shortly before midnight local time (21h30 GMT) military forces and special groups of police closed the area, said another AFP reporter who confirmed the arrival of large number of ambulances and rescue vehicles.
In Paris he reported that President Hollande returned to the capital to take charge of a charter of crisis.
"The president spoke with (Prime Minister) Manuel Valls and (Interior Minister) Bernard Cazeneuve. You will return to Paris directly to the cell of crisis ", the Interior Ministry said the source.
According to initial reports the vehicle, a white van, crashed at high speed into the crowd, sparking a panic, according to an AFP reporter who was in the place.
Witnesses said they heard exchanges of fire, which was not confirmed by the authorities.
"The truck driver seems to have caused dozens of deaths. For now remain in their homes, "he wrote in his Twitter account Mayor Christian Estrosi.
This attack occurs in a context of high risk of attacks by the French authorities, a country that intervenes militarily in Syria against the radical group Islamic State.
Confirmed the casualty figures, would be the third bloodiest attack in Europe in recent years, surpassed by the multiple attacks in Paris in November 2015 (with a balance of 130 dead) and ahead of Brussels in March 2016 with 32 fatalities.