The Islamic State group on Saturday claimed responsibility for the attack in Nice, France, in which 84 people were killed. The terror outfit said the assailant who drove a 25-tonne truck over people watching fireworks during Bastille Day celebrations was a follower of the group, BBC reported. French Interior Minister Bernard Cazeneuve said the attacker "seems to have become radicalised very quickly".

Four people with links to the attacker, who was identified as 31-year-old Franco-Tunisian Mohamed Lahouaiej Bouhlel, have been taken into police custody. While one of them was held the day of the massacre, two others were arrested on Saturday, AFP reported. Witnesses said Bouhlel had driven the lorry in a zigzag in an attempt to injure as many people as possible. He was shot dead after opening fire on security personnel.

President Francois Hollande extended the state of emergency in France by another three months. At least 50 people are still in critical condition, and the toll is expected to rise.