At least three people have been killed and several others wounded after a knife attack inside a cathedral in Nice, France. One of the victims is believed to be beheaded.

The attack took place at 9 am on Thursday morning inside the Notre-Dame basilica in the city centre. There were unconfirmed reports in the French media that at least one of the victims had been beheaded.

The French police described the scene as a "vision of horror".

Christian Estrosi, the Mayor of Nice, said the attacker had repeated "Allahu Akbar" several times while he was being arrested and handcuffed by police.

Estrosi said a woman victim had been decapitated but he had no details of how the two others were killed.

"We have two people killed inside the church … and a third person who was in a bar facing the church where she had taken refuge. Enough is enough … we have to remove this Islamo-fascism from our territory", the Mayor added.

The incident comes two weeks after the horrific killing of 47-year-old teacher, Samuel Paty, by a refugee Islamist terrorist after cartoons of Prophet Mohammed were shown by Paty to his students in a class on freedom of speech.

"Before it was a school professor, this time the Islamo-fascist barbarism chose to attack inside a church. Again, it is very symbolic," Estrosi added.

This is not the first time Nice has come under attack. In 2016, a Tunisian named Mohammed Lahouaiej-Bouhlel drove a 19 tonne cargo truck into the crowds of people celebrating Bastille Day. Eighty-six people were killed and more than 400 injured. The Islamic State claimed responsibility for the attack