Touraine also said one of the hospitalized wounded still has not been identified.
The family of missing UC Berkeley student Nick Leslie, was expected to arrive in Nice to search for the young man, according to NBC San Diego.
He had scouted out the promenade before the attack, CCTV footage showed, and he is said to have sent texts to possible accomplices asking for more weapons.
The anger towards Bouhlel comes amid a growing anti-immigrant sentiment in France and Europe at large in the wake of multiple terror attacks in recent months, including the deadly attacks in Paris in November.
At the Pasteur hospital, where many of them are being treated, emergency responders and other medical personnel gathered in the courtyard for the moment of silence, standing still in a row and clapping when it was over.
There were several placards also spotted in the crowd calling for French President Francois Hollande to resign.
Concerning the questions on the planning and the organization of the Bastille Day firework display in Nice, Valls said, "the investigation will get to the bottom of this".
Reuters could not verify the existence of the photograph, which he declined to share.
The name Mohamed Lahoualej Bouhlel is seen on a plate outside the building where he lived in Nice, France, July 17, 2016.
"He asked for news about our parents... he always spoke to me, we were very close", he added. "He sent us small sums of money recently, sometimes 300 or 400 euros ($330-$440), and mobile telephones".
Though the image of a religious extremist is at odds with the portrait that neighbours and family members painted of a man who ignored even the most basic rules of Islam, by eating pork, drinking alcohol and shunning the mosque.
Molins said that Bouhlel had in the days and two weeks prior to the July 14 attack sought to raise money through a bank loan, which was denied, a cash withdrawal and the sale of his vehicle.
After excelling academically, Bouhlel had drifted away from school, Hamouda said. "He said: 'Why am I thin?'"
French investigators arrested two more people Sunday as they pieced together details about the motives and planning of the Tunisian who rammed a truck into a crowd in an IS-claimed attack that killed 84.
Bouhlel's estranged wife is the mother of Bouhlel's three children and was in the process of divorcing him.
ISIL said it carried out the attack in response to calls to target civilians in countries that are part of a coalition fighting ISIL.
Mangled bodies were left strewn across the Riviera city's seafront in the grisly attack by a man described by those who knew him as a loner with tendencies towards violence and depression.
Bouhlel's father, who lives in Tunisia, said his son had multiple nervous breakdowns and volatile behavior, CNN reported.
But French authorities believe that may have changed. Interior Minister Bernard Cazeneuve told reporters Saturday that Bouhlel "appears to have become radicalized very quickly".
"The individual who committed this absolutely despicable, unspeakable crime was not known by the intelligence services, as he had not stood out over the past years for support of radical Islamist ideology".