He was among dozens of Berkeley students on the program, and fellow students have posted fliers in Nice trying to find him.
In order to stop the truck "you would have needed a concrete wall", said an official. Yasmine, Bouhlel's neighbor, affirmed he was a violent person.
Facing its third major terror attack within 18 months, the French government is coming under fire from opposition politicians and newspapers demanding more than "the same old solemn declarations". Witnesses described seeing how Bouhlel purposely steered the truck to hit men, women and children as they tried to flee. Simpson said "there is still hope he is going to wake up".
Kerry says the US had no knowledge of the killer as a radicalized individual and that if someone is an extremist of "one or two days vintage" it's easy to cause mayhem.
"Investigators still have not discovered a direct link between Islamic State and the attacker, so it is a cheap claim", he said.
Bastille Day revellers were enjoying a live band and fireworks right before the incident, as seen in the footage.
- By Thomas Adamson in Paris.
Hours later, he emerged wailing in distress from the Pasteur Hospital in the north of Nice after learning that his son was also dead.
Many family members have been frustrated by a lack of information about their missing loved ones.
He prayed that God "disperse every plan for terror and for death, so that no man dare spill more blood of his brother".
Francis then offered "a paternal and fraternal embrace for all of Nice's inhabitants and all of France", and invited those in the square to join him in silent prayer for the 84 Nice victims and their families.
"The executor of the deadly operation in Nice, France, was a soldier of the IS", said Amaq, cited by several French media.
Valls has said there were no failures, although Cazeneuve acknowledged on Saturday that the truck had avoided the police vehicles blocking the way to the promenade by mounting a kerb.
"Yesterday in all mosques in the region of Alpes-Maritimes, there has been a common prayer calling for vigilance and patience, because these very bad events affect us; and there has been a call for blood donation", he said.
In a pessimistic interview with the Journal du Dimanche, Manual Valls, the French Prime Minister, has warned that terrorism will be a part of the country's daily life for a long time.
The French health ministry said five children and 21 adults were still fighting for their lives in a critical condition in hospital and were among 121 people still hospitalised.
Speaking to reporters in Nice on Sunday, Touraine said while scores of people who were hospitalized have been released, some may need further medical treatment as their injuries heal.
The claim must be greeted with caution because there was yet no evidence suggesting that the driver was radicalized, or had even been exposed to the Islamic State's propaganda.
As Nice's coastal promenade along the Mediterranean Sea reopened, tourists and residents paid tribute to the 84 people killed and the 200 wounded in Thursday night's attack, their blood still jarringly visible on the pavement.
Valls defended France's record on attacks, saying security services had prevented 16 over three years, and said the modus operandi of cajoling unstable people into striking by whatever means possible was hard to combat.
The estranged wife of the driver is among those being detained. He said he had asked for police to be reinforced in Nice ahead of the fireworks display but was told there was no need. "He executed the operation in response to calls to target citizens of coalition nations, which fight the Islamic State". It's also unclear whether or not Bouhlel, who was shot dead by police that night, had been acting alone.
After Thursday's attack, a state of emergency imposed across France after the November attacks in Paris was extended by three months and military and police reservists were to be called up.