Paris - At least 84 people were killed in the French Riviera city of Nice when a man rammed a truck through a crowd celebrating Bastille Day on Thursday.This is a timeline of the attack that French President Francois Hollande has declared was of "an undeniable terrorist nature".Celebration becomes catastrophe Just before 23:00 local time (21:00 GMT), a white, 19 ton lorry roars down the Promenade des Anglais walkway in Nice, capital of France's Cote d'Azur. Thousands of people had massed there to watch fireworks for France's national day celebrations.The driver runs over adults and children along a 2km path, swerving from the broad footpath back into the street to hit victims near landmarks that include Art Deco casinos and the Hotel Negresco. "We saw people hit and bits of debris flying around," said an AFP reporter who saw the truck drive into the crowd. He described scenes of "absolute chaos".'Appears to have killed dozens' Just before midnight (22:00 GMT), Nice's regional head Christian Estrosi says on Twitter: "The driver of a van appears to have killed dozens. Stay in your homes for now. More info to follow."The truck finally comes to a halt near the Palais de la Mediterranee, a luxury hotel complex. Police and soldiers lock down the scene and other parts of Nice, and witnesses are escorted from the scene with their hands over their heads.Investigators recover ID papers from the truck and later say the driver is Mohamed Lahouaiej-Bouhlel, a 31-year-old Tunisian-born man known to police for minor criminal offences.Local prosecutors say at least 60 people have been killed and scores injured by "a major criminal attack."Children among the dead Just before 04:00 (02:00 GMT) on Friday, Hollande addresses the nation, saying the attack was of an "undeniable terrorist nature", and confirms that several children were among the dead.Hollande announces that a national state of emergency that was to be lifted on July 26 will now be extended for three more months.At 07:30 (05:30 GMT) the interior ministry raises the casualty toll to at least 84 dead, along with 18 people in critical condition and about 50 others with less serious injuries.Messages pour in from global leaders and Sunni Islam's leading seat of learning Al-Azhar condemns the attack, urging unity to "rid the world" of "terrorism."Three days of mourning Hollande decrees a three-day period of national mourning through Monday.A paediatric hospital close to where the attack took place says at least two children have died and around 50 others were being treated, of whom some were "hanging between life and death."