Three people have been killed in a knife attack at a church in France that authorities believe is linked to terrorism.

The stabbing took place at the Notre Dame Church in Nice at around 9am on Thursday.

A suspect was arrested and taken to a nearby hospital after being injured during his arrest, a police official said.

He was believed to be acting alone and police are not searching for other assailants, police added.

Reports suggest an elderly woman was 'beheaded' inside the church, while a man was found with his throat cut.  

The third victim who was stabbed multiple times managed to flee but later died, according to reports.

Joëlle Garriaud-Maylam, member of the Senate of France, said the final words of the third victim were: "Tell my children that I love them”.

Images show the neighbourhood locked down and surrounded by police and emergency vehicles.

The anti-terrorism prosecutor’s office said an investigation was opened into an attack with a terrorist connection after Nice’s mayor Christian Estrosi described the incident as terrorism.

He said the attacker shouted “Allahu akbar!” repeatedly as police apprehended him and that “the meaning of his gesture left no doubt”.

Mr Estrosi said in a tweet said the church caretaker was among those attacked at the Basilica Notre Dame.

Mayor of Nice Christian Estrosi (second left) at the scene where a knife attack took place at a church

He appealed to the citizens of Nice to remain united.

The lower house of parliament suspended a debate on new virus restrictions and held a moment of silence Thursday for the victims.

Watch: Police enter church after stabbings in Nice

The prime minister rushed from the hall to head to a crisis centre overseeing the aftermath of the attack.

The French Council of the Muslim Faith has condemned the knife attack and expressed solidarity with the victims and their families.

Nice’s mayor Christian Estrosi (centre) appealed to the citizens of Nice to remain united

Two separate attacks also took place on Thursday morning - another in France and one in Saudi Arabia.

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

It comes as France is under alert for Islamic extremist acts amid tensions over caricatures of the Muslim Prophet Mohammed published by satirical French weekly Charlie Hebdo.

Less than a fortnight ago, an attacker decapitated a French middle-school teacher who showed caricatures of the Prophet Mohammed for a class on free speech. Those caricatures were published by Charlie Hebdo and cited by the men who gunned down the newspaper’s editorial meeting in 2015.

In September, a man who had sought asylum in France attacked bystanders outside Charlie Hebdo’s former offices with a butcher knife.

Thursday's killings took place less than half a mile from the site in 2016 where another attacker drove a truck into a Bastille Day crowd, killing dozens.