All 84 people killed in the Nice truck attack have now been formally identified, according to a top French official Wednesday, who said the death toll for the Bastille Day carnage has not increased despite several remaining in critical condition.

Prosecutor's office spokeswoman Agnes Thibault-Lecuivre said some of the 84 French and foreign nationals who lost their lives after last Thursday's massacre died subsequently in the hospital.

Authorities have not released an official list naming the dead from the July 14 Bastille Day rampage in the southern French city.

In a speech to army reserves on Wednesday, French President Francois Hollande said 15 people wounded in the Nice attack are still in the hospital "between life and death." He praised the French emergency and security services' work during and after the attack in which Mohamed Lahouaiyej Bouhlel, a troubled 31-year-old Tunisian, drove a truck down a seaside boulevard full of people who had watched a fireworks show.

Officials say that five unnamed people remain in custody for possible links to the attack and two of them have had their detentions extended exceptionally beyond the 96-hour deadline. A sixth unnamed person detained over the attack has been released.