The terrorist attack by Hamas in Israel and the retaliatory strikes in Gaza had already put French authorities on edge, pushing them to jack up security at Jewish sites and ban pro-Palestinian protests.

Then, last Friday, just three days before the country was set to mark the somber anniversary of a teacher’s gruesome beheading by an Islamic extremist, an eerily similar attack hit at home as a man used a knife to kill a teacher and injure three other people at a school in northern France in what officials called an Islamic terror attack.

Since then, the mood in France has gone from worried to alarmed. The authorities raised the terrorist threat alert to its highest level, pouring even more police officers and soldiers onto the streets. Bomb scares emptied out major sites over the weekend, including the Louvre and Versailles Palace.

Officers in flak jackets with machine guns, their fingers resting on the triggers, stood sentinel on Saturday outside the school where a former student went on a stabbing spree the day before, killing Dominique Bernard, 57, a French literature teacher.

Mourners arrived bearing bouquets of white roses. Many were racked with grief but also were wondering anxiously whether the escalating crisis in the Middle East had stoked the embers of Islamic terrorism and blown them to a small northern French city.

“We are on the other side of the world, but we are facing the consequences,” said David Milhamont, with his son Valentin, 11, who was scurried out of the attacker’s path on Friday by a hall monitor and sheltered in a classroom. “Just how far it will go, that is the question.”

The suspected attacker, Mohammed Mogushkov, 20, is in custody.

The sense of anxiety has been compounded by the ominous timing of the attack — almost three years to the day after the brutal murder of Samuel Paty, a history teacher who was beheaded by an Islamic extremist for showing caricatures of the Prophet Muhammad in his class to illustrate free speech, a killing that deeply traumatized the country.

Prescheduled ceremonies in schools across the country to honor Paty on Monday were suddenly painfully relevant.

“Islamist terrorism has struck at what it rightly regards as its greatest adversary: our schools,” President Emmanuel Macron said in a message to teachers.

“Terrorists know that there can be no Republic without schools, without patiently learning in your classrooms about critical thinking and the values of liberty, equality, fraternity and secularism that forge citizens,” he said.

The attack also came the morning after Macron reiterated the country’s unwavering support for Israel in the wake of the terrorist attacks by Hamas. French authorities have raised the possibility that there was a link between Friday’s attack and the conflict but have offered little concrete evidence.

Home to some of Europe’s largest Muslim and Jewish communities, France has been on alert since the conflict started when Hamas invaded Israel on Oct. 7. There have been nearly 200 antisemitic acts, mostly verbal threats and vandalism, and over 100 people have been arrested for such acts or for glorifying terrorism, according to Interior Minister Gérald Darmanin.

By Catherine Porter and Aurelien Breeden