Djaziri, who died from an apparent cardiac arrest during the attack, had packed two full 13-kilogram gas bottles into his vehicle as well as a bag full of projectiles, Molins told a press conference on Thursday afternoon.
The arms cache found at the 31-year-old's home were signs of the "indisputable preparation of violent action", he added.
Molins also revealed that Djaziri's "testament", which he sent to a number of acquaintances on the day of the attack, showed he had wanted to go to join Islamist fighters in Syria but complained that he had been prevented from doing so by "apostates who [were] against the Islamic State".
The four members of Djaziri's family who were detained on Monday were released without charge on Wednesday evening.
His father, ex-wife, brother and sister-in-law were all taken into custody shortly after the attack.