World Bulletin / News Desk
The Nice-Matin newspaper did not name the man but said his identity documents were found in the truck that mowed down crowds of people celebrating Bastille Day on Thursday night and his identity confirmed through fingerprints.
He was reported to be known to police for non-extrem-related offenses. The newspaper said police were searching his home.
Meanwhile, Prime Minister Manuel Valls announced a three days of national mourning from Saturday. “The goal of extremists is to instill fear and panic but France is a great country and a great democracy that will not allow itself to be destabilized,” he said in televised remarks from Paris.
He added: “We want to achieve the unity of the nation. The only answer should be that of a united France.”
The prime minister said an extension to the state of emergency that has been in place since November’s attacks in Paris killed 130 would be discussed by the Cabinet and in parliament next week.
Before the Nice attack, it had been due to end on July 26 but will now run for a further three months.
After returning to Paris from Avignon in the south of France, President Francois Hollande held a security meeting at the Elysee Palace.
“France has been struck on the day of her national holiday -- July 14, Bastille Day -- the symbol of liberty, because human rights are denied by fanatics and France is clearly their target,” he said following the meeting.
The president said the extremist nature of the attack “cannot be denied” and declared France was under threat from “Islamist extremism”. The attack would “strengthen our efforts in Syria and Iraq against those who are attacking us on our very soil,” he added.
The attacker drove a white truck 2 kilometers (1.2 miles) through crowds of revelers who had been watching a fireworks display from the Promenade des Anglais.
Witnesses said the driver, who was killed in the attack, was zigzagging in an attempt to hit people and began shooting randomly after getting out of the truck. One told broadcaster BFMTV that he saw other men with guns in the truck. French authorities are working to determine if the attacker had any accomplices.