PARIS — Four police officers were killed in a stabbing early Thursday afternoon at police headquarters in central Paris, according to French officials.

The alleged assailant, shot dead at the scene, was a 45-year-old man who had served as an employee of the police department’s administrative staff for 20 years, according to Loïc Travers, a regional official for Paris’s Alliance Police Nationale union, speaking to reporters on France’s BFMTV network.

The suspect’s motives were unclear to French authorities. Christophe Castaner, France’s interior minister, said the man had “never presented behavioral difficulties, nor the slightest sign of alarm.” Remy Heitz, the Paris prosecutor, announced that his office was opening an investigation.

The incident immediately drew national attention. The area surrounding the police headquarters – on the Ile de la Cite, near Notre Dame Cathedral – was cordoned off. Politicians observed a moment of silence Thursday afternoon.

President Emmanuel Macron went to the scene, although he did not cancel plans to attend a debate over retirement issues in southern France on Thursday evening.

“Paris is mourning her own this afternoon after this appalling attack on the @prefpolice,” Paris Mayor Anne Hidalgo said on Twitter. “The toll is heavy; several policemen lost their lives. In my name and that of Parisians, my first thoughts go to the families of the victims and their relatives.”

The attack occurred a day after a large protest by police officers in the French capital.

According to the event’s organizers, more than 27,000 turned out Wednesday to protest high rates of suicide among officers and the proposed changes to the department’s retirement plan.

The killing of police officers has punctuated French public life in recent years. In April 2017, Xavier Jugele, 37, was killed in Paris on the eve of the French presidential election. In March 2018, Arnaud Beltrame, 44, was killed in a standoff in the southwestern French city of Carcassonne, where he died after exchanging himself for a hostage.

“We will pay tribute to the victims and we will salute the unwavering commitment of members of the police to the safety of Parisians,” Hidalgo said in her statement. “We know what we owe them.”

Comments are not available on this story.