Man attacks police officer with hammer in Paris

"Situation under control, one policeman injured, the assailant was neutralized and taken to hospital", Paris police said on Twitter. The officer fired his gun, striking the attacker.

The incident followed two other attacks on soldiers protecting prominent Paris sites, one in February at the Louvre museum and another at Orly airport in March.

France remains under high alert following a string of attacks in recent years.

Karine Dalle, a spokeswoman for the Paris archdiocese, said in a text message that the roughly 900 people inside the cathedral were notified about the violence and were "sitting calmly" until they were permitted to leave.

Hundreds of tourists were inside the cathedral when the attacker struck.

Journalist David Metreau, who said his office overl.

Others posted photos online of what appeared to be the interior of medieval Notre Dame, one of France's most-visited monuments.

Cops have warned members of the general public to stay away while a "security operation" is underway but refused to provide further details at this time.

The video pledging allegiance to the jihadist group was found in a police search of an apartment he was renting in Cergy outside Paris, the source in the investigation said. The square was evacuated.

Police sealed off the area in front of the cathedral, where the attacker lay injured on the ground.

France unveiled on Wednesday a new counter-terrorism task force a day after a hammer-wielding man attacked police officers near Notre Dame Cathedral in Paris.

"We have passed from a very sophisticated terrorism to a terrorism where any instrument can be used for attacks", Mr Collomb said.

"Obviously, this attack could have been far more serious if his colleague had not reacted so quickly".

Police warned tourists to stay away from the area as they continue their investigation.

On Tuesday, a 40-year-old Algerian had threatened police officers with a hammer and refused to stop. A police official would not provide further information.