Police have reportedly praised a heroic member of the public for jumping into a truck and wrestling with its murderous driver as it tore through throngs of men, women and children celebrating Bastille Day in Nice on Friday.

French delegate Eric Ciotto told radio station Europe 1 that a man jumped into the truck and tried to stop the driver as the vehicle ploughed through the crowd in the French coastal city.

Forensic police officers examine the truck after the deadly attack. Credit:AP

Mr Ciotto said the man's efforts enabled the police to intercept the killer, 31-year-old French Tunisian Mohamed Lahouaiej Bouhlel.

"It's at that moment that the police were able to neutralise this terrorist," Mr Ciotto told Europe 1. "I won't forget the look of this policewoman who intercepted the killer."