Police in Paris have shot a man who attempted to attack an officer outside Notre-Dame cathedral.

Authorities, who are investigating the incident as a potential terror attack, asked members of the public to stay away from the area during ongoing operations.

The man attacked an officer with a hammer before one of his colleagues opened fire and “neutralised” him, officials said.

French police stand at the scene of a shooting incident near the Notre Dame Cathedral in Paris, France on 6 June 2017 (Reuters)

French interior minister Gerard Collomb said the attacker shouted “this is for Syria”.

A spokesperson for Paris’s prefecture of police said the officer was wounded and the assailant was taken to hospital, adding the situation was now “under control”.

Kellyn Potvin-Gorman told the BBC she was having her bag checked at security checkpoints at the cathedral’s entrance when she heard gunfire.

“I turned around and saw the assailant on the ground where they had shot him,” she added.

“There were tonnes of people running in all directions, and we were brought inside at that time.”

Speaking from inside Notre-Dame, Ms Potvin-Gorman said the attacker was “taken down immediately”, adding: “He had no chance whatsover...he was face down on the pavement.”

Hundreds of tourists and passers-by were locked inside the famous cathedral as the operation continued.

They were gradually released after around an hour, following “routine” security checks.

Officers cordoned off a large part of the Île de la Cité as a precaution for searches for potential accomplices or suspect devices.

The counter-terrorism unit of the Paris prosecutor’s office has opened an investigation into the incident.

Le Louvre evacuated after soldier opens fire on 'attacker'

France remains under a state of emergency that has been repeatedly extended in the wake of the Charlie Hebdo massacre, Paris attacks, Nice attack and series of murders by Isis supporters.

The atrocities have killed around 240 people in France since the start of 2015.

Soldiers patrolling its streets alongside police to protect tourist sites, government buildings and events have been the target of attempted attacks, including at Paris-Orly airport and outside Le Louvre.

Several terror plots have been disrupted in recent months, seeing the arrest of three women after police found a car laden with gas cylinders was abandoned near Notre-Dame cathedral for what authorities described as an “imminent” attack.

Isis has called for supporters around the world to carry out intensified terror attacks during the Islamic holy month of Ramadan, as it seeks to maintain momentum while losing territory in Syria and Iraq.