The maternity hospital was hit by a blaze early on Wednesday, causing tragedy for dozens of parents.
The 15-year-old is the son of an imam that Belgium is attempting to deport to the Netherlands.
The Pakistani Taliban vowed more attacks "until the imposition of an Islamic system in Pakistan."
Friends of Sankari said he had been threatened by gangs because of his sexuality.
Bangladeshi police also arrested a University of Toronto student.
Police named the first attacker as 19-year-old Adel Kermiche, who was wearing an electronic tag.
A French counter-extremism court formally charged two Albanians and three Tunisians on Thursday.
The truck attack involved five further suspects who are in custody, Paris prosecutor said.
Fatima Charrihi, 62, was on the Promenade des Anglais with her family last Thursday.
An old friend says the delivery driver may have been scarred by a turbulent relationship with his father.
French authorities made the discovery on Bouhlel's phone after his truck attack on Thursday.
Extremism has taken a hold in the French Riviera city, leaving its Jewish community on edge.
The Muslim community in the French city is angry that another Muslim man has committed violence in the name of Islam.
The residents of this French Riviera city say a deadly attack was only a matter of time.
The French premier declared three days of national mourning and said the government would look to extend the state of emergency.
The Islamic State militant group has called on its followers to commit attacks during the Muslim holy month.
Security services foiled the plot two weeks ago, arresting 10 militants and seizing explosives.
The cell planned to strike the Park Mall in the eastern city of Setif, according to a government newspaper.
The FBI says that it is not aware of any credible threat to both cities.
Four suicide bombers detonated explosive devices near the border with Syria.
The intelligence ministry said it has made multiple arrests connected to a bomb threat.
The group is punishing those suspected of eating or drinking during daylight hours in the Islamic holy month.
Experts says his proposal for suspending immigration from places with a history of terrorism could have a legal basis.