PARIS.- Thousands of troops were being deployed to guard sensitive locations across France, and the Louvre Museum and the Palace of Versailles were evacuated in separate security alerts, as the country remained on edge Saturday after the killing of a schoolteacher in a stabbing attack that authorities described as an act of Islamic terrorism.

France has been under its highest terrorist threat level since Friday, when the teacher, Dominique Bernard, was killed at a school in Arras, in northern France. A suspect was quickly arrested at the scene: Officials said he was a former student of Bernard’s and had already been under surveillance as a potential Islamic extremist.

On Saturday morning, the Louvre, the world’s most visited art museum, ushered visitors out and closed its doors in response to “a written message that there was a risk,” said Coralie James, a spokesperson for the museum. “In the current national context,” she added, the museum had decided to shut for the day, “while we carry out the necessary checks.”

And on the outskirts of Paris, another treasure of French heritage, the Palace of Versailles — built for King Louis XIV — was also evacuated, police said Saturday afternoon. In a statement on X, formerly known as Twitter, they said a suspicious package had been found.

Earlier in the day, authorities announced the mobilization of troops dedicated to responding to a potential terrorist attack. French Defense Minister Sebastien Lecornu wrote on X that up to 7,000 soldiers were being deployed to strengthen security at sensitive sites, at the request of President Emmanuel Macron.

The suspect in Bernard’s stabbing was identified by officials as Mohammed M., a Russian immigrant born in 2003. In addition to killing Bernard, who taught French literature, the attacker injured a physical education teacher and two other school employees.

Interior Minister Gérald Darmanin said in an interview Friday on TF1 television that intelligence services had recently been tipped off that Mohammed M. had been in touch with other radicalized people, including his brother.

Raising the threat level in the country was precautionary, Darmanin said, and authorities had not detected any specific threats. But, he added, there was “probably” a link between the attack and the current conflict between Israel and Hamas — part of an “extremely negative atmosphere,” he said.

This article originally appeared in The New York Times.