Shoppers in Nice fled in terror as the sound of gunshots filled the air outside Notre Dame Cathedral following a deadly suspected terror attack.

Dramatic footage records the sounds of what is believed to be police opening fire on the suspect in the mass stabbing.

A second clip captures police storming the cathedral and opening fire while people scream, and witnesses watching from a balcony exclaim in shock.

Three were killed in the attack on the church, and officials confirmed two of the victims were beheaded in this morning's horror, in which several more people were wounded.

The city's mayor said the incident at 9am today was being treated as a terror attack, and claimed police had shot the knifeman then rushed him to hospital.

Twitter user Emyllianna posted a video online capturing the moments before the sound of a series of rapid-fire gun-shots filled the streets.

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Police storm the basilica as people watch from a balcony overlooking the scene

She wrote in French: "I was there when the shooting started.

"A man had hidden inside Notre Dame and then lots of police arrived. He tried to run out of the cathedral and the police shot him."

In the clip, a group are standing talking in the street as police surround the perimeter.

In the clip, a motorbike pulls up at speed, then a series of shots can be heard, and the sound of someone screaming in the distance.

A man nearer the camera says 'run' and another man can be heard shouting in the distance.

The sounds of gunshots were heard as officers rushed into the church
Dramatic scenes are filmed as police storm the Roman Catholic church

The group begins to flee, away from the direction of the sounds of gunfire.

The group run into a shop, and a woman can be overheard thanking the staff for letting them shelter inside.

The witness who posted the video tweeted to concerned well-wishers that she was safe.

Another video shot from a balcony overlooking the church shows one police officers rushing in, and the sounds of gun-shots as more indoors open fire.

Gunshots and screams are heard as shoppers flee

The person filming can be heard to exclaim in horror as an officer rushes towards the steps of the basilica, where his colleagues are inside.

Birds nesting around the church go flying as the sounds of gunshots fill the air, and screams can be heard in the distance.

The officer on the steps then pulls back, as more police come running outside.

Nice Mayor Christian Estrosi said the attacker was heard to shout the phrase 'Allahu Akbar'  – which translates from Arabic to ‘God is the Greatest’ before being shot by police.

An officer is poised outside the building as shots are heard in the church

One of the victims killed was said to be the church warden, the mayor added - while another of the victims who was beheaded was a woman.

One woman who was gravely injured, had tried to escape from the church and had run into a bar opposite the building.

French media are reporting a woman had died after fleeing to a bar across the road.

French forces guard the streets following the attack

French President Emmannuel Macron paused a coronavirus lockdown debate to head to the scene of the attack this morning.

The leader had announced a second national lockdown only yesterday.

Nice's mayor said the victims had been killed in a "horrible way".

A major police operation is underway following the carnage this morning

"The methods match, without doubt, those used against the brave teacher in Conflans Sainte Honorine, Samuel Paty," Mr Estrosi said.

He was referring to the beheading earlier this month of French middle school teacher Samuel Paty by a man of Chechen origin.

France is still reeling after the incident, on which the attacker had said he wanted to punish Paty for showing pupils cartoons of the Prophet Mohammad in a civics lesson.

Three died and several more were wounded in the attack

It was not immediately clear what the motive was for the Nice attack, or if there was any connection to the cartoons, which Muslims consider to be blasphemous.

A few hours after the incident in Nice, a man was reportedly shot dead in Avignon after threatening people with a knife and shouting 'Allahu Akbar'.

And a guard was stabbed at a French consulate in Jeddah, Saudi Arabia this morning, also within hours after the Nice attack.

It remains unclear whether the incidents are related.

France has now raised its security alert to the highest level.

Prime Minister Jean Castex said also told French National Assembly that the government's response to the attack would be firm.