The Islamic State group has claimed responsibility for the truck attack in the French city of Nice as police arrested three more people in relation to the carnage that claimed the lives of at least 84 people.
"The person who carried out the operation in Nice, France, to run down people was one of the soldiers of Islamic State," the news agency Amaq, which supports the militant Islamist group, said via its Telegram account.
"He carried out the operation in response to calls to target nationals of states that are part of the coalition fighting Islamic State."
French authorities and media have yet to produce any evidence that the killer, Mohamed Lahouaiej Bouhlel, was radicalised — the interior ministry said it was checking the claim.
The 31-year old Tunisian, who lived locally,zigzagged through a Bastille Day crowd for nearly two kilometres on the waterfront of the French Riviera city on Thursday night — it was eventually stopped when police shot dead the driver.
At least 10 children and teenagers were killed, with around 50 other children injured, some of them "hanging between life and death", a hospital official said.
Authorities had been working to find out what his motives were — he was not known to French intelligence sources for radicalisation.
Bouhlel was known to police for petty crimes but was not on a watch list of suspected militants.
He had one criminal conviction for road rage, having been sentenced to probation three months ago for throwing a wooden pallet at another driver.
The arrests, which came on top of two others since the killing including the attacker's wife, concerned his "close entourage", police sources said — they were made in two different areas of Nice.
A Reuters journalist reported that about 40 elite police raid a small apartment near the central station, where one individual was arrested.