A man was shot and injured after he reportedly attacked a police officer with a hammer at Notre Dame Cathedral in Paris on Tuesday.
Police warned people to stay away from the French landmark, on the Ile de Cite island on the River Seine, via Twitter message.
The officer was injured during the assault and the attacker was shot by his colleagues, The Sun reported.
The area in front of the Cathedral was sealed off, with French TV reporting that tourists were fleeing the scene.
A journalist with channel Europe 1 said an attacker lunged at an officer with a hammer.
Texan tourist Amanda Beasley said: "Just witnessed a shooting on the square in front of the Notre Dame.
"We ran for cover and were able to escape unharmed. We are all safe. One attacker was shot and the police are still trying to locate others."