French police say they have shot a man outside the cathedral of Notre-Dame in Paris, after he tried to attack an officer using a hammer.
The suspect has been wounded in the chest, French media report.
The shots prompted panic among visitors. The area around the cathedral has been closed and people are being asked to stay away.
France is in a state of emergency since attacks by jihadists in Paris left 130 people dead in 2015.
The man attacked officers on duty at the Paris police headquarters, which is next to the cathedral, French media say.
Eyewitnesses said tourists fled for cover.
The attack comes just three days after extremists used a van and knives in an attack in London which left seven dead.