Update : French Interior Minister Gerard Collomb says the attacker cried "it's for Syria" as he went after officers patrolling an esplanade in front of the famous landmark.

Notre Dame attacker appeared to be acting alone.

Notre Dame attacker had hammer, kitchen knives.

Notre Dame attacker had identity card of Algerian student.

Paris prosecutors have opened a counterterrorism investigation after an unidentified assailant attacked police with a hammer outside Notre Dame Cathedral.

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As we detailed earlier, The BBC reports that police are responding to an alert at Paris's Notre Dame cathedral amid reports of gunshots and panic.

Le Parisien confirms an incident...

La préfecture de police conseille d'éviter le secteur du Parvis de Notre-Dame. https://t.co/INGg7EYhm3 — Le Parisien (@le_Parisien) June 6, 2017

The Telegraph reports a policeman has shot a man after he tried to assault him with a hammer near Notre Dame. It is understood that the main square has been evacuated and that a police operation is underway.

Eyewitnesses said they saw a man lying on the ground.

Police have warned "Square in front of Notre Dame Intervention being the number of police, avoid the area"...

????Parvis de #NotreDame Intervention en cours des effectifs de police, évitez le secteur — Préfecture de police (@prefpolice) June 6, 2017

Sky reports that the French prosecutor's office says the country's counter-terrorism office has opened an investigation following the Notre Dame Cathedral incident.

Valeurs reports that 900 people are currently confined inside Notre-Dame Cathedral.

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