Athens City Hall is illuminated in the colors of the French national flag in memory of the victims of the Nice attack and in solidarity with the French people in Athens, Greece on July 15, 2016. French Prosecutor of the Republic Francois Molins announced Friday in a press conference that 84 people, including 10 children and adolescents, were killed Thursday night in Nice during a terrorist attack. Photo:Xinhua

People gather to mourn victims of an attack in which a truck drove through crowds during Bastille Day celebrations in Nice, France on July 15, 2016. People in the wake of the deadly Nice attack on Thursday, French Prime Minister Manuel Valls on Friday morning declared three days of national morning, to begin on July 16.Photo:Xinhua

Photo taken on July 15, 2016 shows a black ribbon on a French national flag in Nice, France. People in the wake of the deadly Nice attack on Thursday, French Prime Minister Manuel Valls on Friday morning declared three days of national morning, to begin on July 16.Photo:Xinhua

People gather to mourn victims of an attack in which a truck drove through crowds during Bastille Day celebrations in Nice, France on July 15, 2016. People in the wake of the deadly Nice attack on Thursday, French Prime Minister Manuel Valls on Friday morning declared three days of national morning, to begin on July 16.Photo:Xinhua

People gather to mourn victims of an attack in which a truck drove through crowds during Bastille Day celebrations in Nice, France on July 15, 2016. People in the wake of the deadly Nice attack on Thursday, French Prime Minister Manuel Valls on Friday morning declared three days of national morning, to begin on July 16. Photo:Xinhua

A woman places flowers outside the French embassy to mourn victims of an attack in which a lorry drove through packed crowds gathered for Bastille Day celebrations in the French city Nice, killing at least 84 people, in London, Britain on July 15, 2016.Photo:Xinhua