Three people have been killed in a knife attack in the French city of Nice, police say.

Nice Mayor Christian Estrosi said there had been a “terrorist attack at the heart of the Notre-Dame basilica”.

One elderly victim who had come to pray was “virtually beheaded”. A suspect was shot and detained shortly afterwards.

Mr Estrosi spoke of “Islamo-fascism” and that the suspect had “repeated endlessly ‘Allahu Akbar’ (God is greatest).”

France’s national anti-terror prosecutors have opened a murder inquiry. Mr Estrosi compared the attack to the recent murder of teacher Samuel Paty, who was beheaded close to his school outside Paris earlier this month.

Two further attacks took place on Thursday morning, one in France and one in Saudi Arabia.

A man was shot dead in Montfavet near Avignon after threatening police with a handgun. And a guard was attacked outside the French consulate in Jeddah. A suspect was arrested and the guard taken to hospital.

Police have not suggested a motive for the attack. However, it follows days of protests in some Muslim-majority countries triggered by President Macron’s defence of French cartoons that depict the Prophet Mohammed. There have been calls in some countries for a boycott of French goods.

Two of those who died were attacked inside the church, the elderly woman and a man who was found with his throat cut, reports said.

A woman managed to flee to a nearby cafe after being stabbed several times, but died later.

It later emerged that a witness had managed to raise the alarm with a special protection system set up by the city.

Chloe, a witness who lives near the church, told the BBC: “We heard many people shouting in the street. We saw from the window that there were many, many policemen coming, and gunshots, many gunshots.”

Tom Vannier, a journalism student who arrived at the scene just after the attack, told the BBC that people were crying on the street.