Police have shot a man who attacked an officer with a hammer outside the Notre-Dame cathedral in Paris.
The man shouted "This is for Syria" during the attack, officials say. Authorities are treating it as a terrorist incident.
The officer suffered minor injuries. The suspect was wounded in the chest when another policeman opened fire.
Tourists fled for cover as the attack unfolded. Hundreds of people were at the cathedral at the time.
France is in a state of emergency since attacks by jihadists in Paris killed 130 people in 2015.
French Interior Minister Gérard Collomb said that the assailant on Tuesday afternoon had carried the identity card of an Algerian student.
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Anti-terrorist prosecutors have opened an investigation.
Paris police said on Twitter that the situation was now "under control" and that the hundreds of people who were inside the cathedral would slowly be allowed out.
Kellyn Gorman, an American tourist, said: "I was about to come inside [the cathedral] and heard the noise, the gunshots, turned around and saw the assailant on the ground where they had shot him."
"It was very safe, very quickly contained.
Notre-Dame is one of the most visited tourist sites in Paris. Last year, police foiled an attack near the site.
The incident comes just three days after militants used a van and knives in an attack in London which left seven dead.