NICE: In a statement carried by a media outlet of the so-called islamic state (IS), the group has claimed the truck attack in Nice, France.

IS on Saturday claimed the Tunisian man, who barrelled his truck into a crowd in the French resort city, was a “soldier” of the group. This is the first claim of responsibility for the July 14 attack that has claimed 84 lives and wounded more than 200 people.

The statement didn't name Mohamed Lahouaiej Bouhlel, the 31-year-old Tunisian who authorities say was behind the wheel as his truck crashed into a crowd of revellers at a fireworks display on Thursday. But the statement quoting a security member of the group said the man was following calls from IS to target nationals of countries fighting it.The nature and scope of Bouhlel's relationship with IS hasn't been established.

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It's also unclear whether or not he was acting alone.

The Paris prosecutor's office said Saturday that five people are in custody following the attack.The identities of most of those brought into custody were not clear. But neighbours in the Nice neighbourhood where the Bouhlel used to live told The Associated his estranged wife had been taken away by police on Friday.

The claim of responsibility came as French security chiefs met in Paris as Nice's seaside boulevard partially reopened to traffic. An Associated Press reporter at the site of the massacre, Nice's famous Promenade des Anglais, said the boulevard was slowly coming back to life. A makeshift memorial of bouquets, candles and messages had been set up near one end of the expansive avenue.France is observing three days of national mourning in homage to the victims.

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Following the attacks, France's interior minister had said, "We are in a war with terrorists who want to strike us at any price and in a very violent way".

Even in the absence of official confirmation, IS Twitter accounts were celebrating the carnage, the Independent had reported. Kilafa News, considered to be an official IS channel had asked supporters to “show the world the truth about the war on the Islamic state and how they brought this to themselves,” the message read. “Use any Islamic state material and reveal the truth for the world”.