Nice Mayor Christian Estrosi has confirmed that one person has been arrested as he said that the incident was a "terrorist attack at the heart of the Notre-Dame basilica".
According to reports in the international media, Mayor Estrosi told the local reporters that the suspect "endlessly repeated Allahu Akbar" even after he had been arrested.
Videos and footages shared on Twitter revealed chaotic scenes outside the church. Take a look:
A minute's silence was observed in the National Assembly, where French Prime Minister Jean Castex was detailing the nationwide lockdown, which will come into effect on Thursday night.
"Without question, this is a very serious new challenge that is striking our country," the BBC quoted Castex as saying.
Police have confirmed that three people have died in the attack while several others have been injured. The French anti-terrorism prosecutor’s department will be investigating the attack.
Indian Prime Minister Narendra Modi sent condolences to the families of the victims on Twitter while condemning "the recent terrorist attacks in France, including today's heinous attack in Nice inside a church". "India stands with France in the fight against terrorism," he wrote.
The fresh incident of violence comes at a time when France is trying to recover from the effects of another shocking killing of a French middle school teacher Samuel Paty that happened earlier this month in Paris. The teacher was murdered for showing controversial Charlie Hebdo cartoons in his class.
The French government and especially President Emmanuel Macron have recently been mired in debate and controversy over allowing French weekly satirical magazine Charlie Hebdo to publish cartoons that are being deemed as being blasphemous or hurtful by the Muslim community. In certain countries like the UAE and Saudi Arabia, people went ahead to opt for a boycott of French products over the issue.