The truck drove 1.2 miles through the crowd before stopping, according to prosecutor Jean-Michel Pretre, causing dozens of fatalities.
According to eyewitnesses, truck accelerated as it ran into the crowd and zigzagged in order to cause more casualties. The driver reportedly exited the vehicle with a firearm, resulting in a shootout with police. The driver was shot and killed by the authorities.
French newspaper Le Figaro reports that grenades and firearms were found in the back of the truck.
The incident occurred on Promenade des Anglaise, a popular tourist location along the waterfront, where a crowd had gathered to celebrate Bastille Day.