The terrorist who killed three people in an attack on a Catholic church in France was a 21-year-old Tunisian. 

According to media reports, Brahim Aoussaoui travelled to Europe in a migrant boat last month before making his way to France. 

He entered the Notre Dame basilica in Nice at 8:30am on Thursday morning and shouted 'Allahu Akbar' (God is greatest) as he carried out a knife attack on worshippers around half an hour later. 

One 60-year-old woman was "virtually beheaded" in the attack. The other two victims have been named as 54-year-old sacristan Vincent Loques and 44-year-old mother of three Simone Barreto Silva. 

Aoussaoui was shot 14 times by police before being arrested. Another man was arrested last night on suspicion of being an accomplice. 

Cardinal Vincent Nichols, leader of the Catholic Church in England and Wales, said he was "horrified" by the attacks.

"People have been killed in a sacred place, which they had entered in order to pray. I know the Basilica well. It is much loved by the people of Nice and by so many visitors," he said. 

"Its violation deepens the horror of three brutal killings. May these three innocent people rest in peace. May all people reject utterly the pathway of senseless violence. May God bless Nice." 

The Archbishop of Canterbury, Justin Welby, was among those offering his condolences to the people of France. 

"I'm praying for the nation of France, and for the friends and relatives of those murdered in Nice today," he said.

"That this should have taken place in church, a house of prayer, underscores the godlessness of the attack." 

French President Emmanuel Macron was in Nice yesterday where he visited the scene of the attack. 

He said soldiers would be deployed to places of worship to step up security. 

The French government has raised the country's terror alert to the maximum level following the church attack, which came just weeks after a school teacher was murdered in a Paris suburb after showing students cartoons of the Prophet Muhammad. 

The attack on the church followed a press release by al-Qaeda calling for 'jihad' in response to newspaper Charlie Hebdo's cartoons of the Prophet Muhammad.