Four men believed to be linked to the man who killed 84 people on Bastille Day in Nice are in police custody, French media have reported.
One of the men was arrested Friday and three others on Saturday morning, AFP reported.
Emergency services crowd the street following the deadly attack on Bastille Day. Photo: AFP
Mohamed Lahouaiej-Bouhlel, a 31-year-old Tunisian, drove a 19-tonne truck through crowds marking Bastille Day on the Promenade des Anglais on Thursday (Friday NZT) before he was shot dead by police.
Militant group Islamic State tonight claimed responsibility for the attack, saying it was carried out by one of its "soldiers" in response to its calls to target those in the US-led coalition against it.
Authorities in France were still trying to determine whether Lahouaiej-Bouhlel acted alone or with accomplices, and whether his motives were connected to radical Islam.
They said they were checking the militant group's claim of responsibility.
Police sources told Reuters the arrests on Saturday concerned the attacker's "close entourage" and were made in two different areas of Nice. A Reuters reporter saw about 40 elite police raid a small apartment at Rue Miollis, north of the central station, where one individual was arrested.
Lahouaiej-Bouhlel's ex-wife was earlier also taken into police custody.
An image obtained from a French police source shows a reproduction of the residence permit of Mohamed Lahouaiej-Bouhlel. Photo: AFP
French President Francois Hollande will chair crisis talks later, and the country has entered three days of national mourning for the victims of the attack.
Mr Hollande, who has said the attack was of "an undeniable terrorist nature", has already extended a state of emergency by three months.
He warned that the battle against terrorism would be long, as France faced an enemy "that will continue to attack those people and those countries that count liberty as an essential value".
Prosecutors said Lahouaiej-Bouhlel drove the lorry 2km along the promenade targeting people.
Ten of the dead were children. Some 202 people were injured; 52 are critical, of whom 25 are on life support.
At the meeting with the security chiefs, Mr Hollande was expected to review all options in response to the attack.
A state of emergency had been in place across France since November's Paris attacks, carried out by militants from Islamic State, in which 130 people died. It had been due to end on 26 July.
Some 30,000 people were on the Promenade des Anglais at the time of the attack, officials said.
Residents of Nice and foreign tourists were killed, among them four French citizens, three Algerians, a teacher and two schoolchildren from Germany, three Tunisians, two Swiss, two Americans, a Ukrainian, an Armenian and a Russian.
Paris prosecutor Francois Molins said the attack bore the hallmarks of jihadist terrorism.
Lahouaiej-Bouhlel was known to the police as a petty criminal, but was "totally unknown to intelligence services... and was never flagged for signs of radicalisation," the prosecutor added.
Relatives and neighbours in Lahouaiej-Bouhlel's home town of Msaken outside the coast city of Sousse told Reuters he was sporty and had shown no sign of being radicalised, including when he last returned for the wedding of a sister four years ago.
- BBC / Reuters
