A man wielding a knife tried to attack police during a ceremony beneath the Arc de Triomphe monument in Paris on Friday, and was shot and injured by police, officials said.

The attacker targeted an officer securing the ceremony for relighting the eternal flame honoring unknown soldiers at the Napoleon-era landmark, according to a Paris police official. Another officer shot the attacker, who was hospitalized, the official said.

No bystanders or police officers were injured in the incident, the official told The Associated Press. The French counterterrorism prosecutor’s office said it is investigating the case and sent an investigator to the scene.

French newspaper Le Parisien said an individual attacked one of the officers with a knife “for an undetermined reason,” according to a source close to the investigation. It happened at around 6 pm this Friday when three members of the mobile gendarmerie were at the Arc de Triomphe for the ceremony to rekindle the flame of the Unknown Soldier, the newspaper also reported. 

The alleged attacker was “neutralized” and was taken to hospital in critical condition. The attacked officers sustained minor injuries. The Charles-de-Gaulle-Etoile station, located on metro lines 1 and 6 and RER line A. 

The National Anti-Terrorist Prosecutor’s Office (PNAT) has taken over the investigation, local media also reported.

The Arc de Triomphe is one of Paris’ most famous sites, and sits atop the busy Champs-Elysees avenue.