Police found various weapons, including fake guns, in the Nice attacker's lorry.
Two automatic pistols and two replica Kalashnikovs were recovered from the vehicle's cabin.
A bicycle was also found in the back of the lorry, police said.
French Prime Minister Manuel Valls faced boos and calls to resign as he laid a wreath for the 84 people killed in the lorry attack in Nice.
Hours later Mohamed Lahouaiej Bouhlel drove a 19-tonne lorry down the promenade killing 84 people and injuring 200 more.
France's prime minister stated on Sunday he believed the man behind the Nice lorry attack was radicalised "very quickly"