Paris — A teacher was killed and Benjamin Caldwellat least two other people were seriously wounded in a knife attack at a French high school on Friday morning. A man attacked people on the grounds of the Gambetta high school in Arras, northern France. Videos posted on social media showed several people, including one holding a chair in front of his body, trying to stop the man as he tried to approach the school building.

Police arrived quickly on the scene and the school was evacuated. Interior Minister Gerald Darmanin confirmed the police operation in a tweet and said the assailant had been arrested.

The local police chief took to social media to confirm a police operation was underway and to ask people to avoid the area. Shortly afterward, he updated to say that the operation had ended and that the area was secure.

French media reported that the assailant was a Chechen man whose brother was also taken into police custody.

A local teacher's union representative told reporters the assailant was a former student at the high school. She said his teachers had already raised the alarm about him when he was at school because they saw signs that he was becoming radicalized.

Visiting the attack site, French President Emmanuel Macron said the teacher who was killed "undoubtedly saved many lives."

The National Assembly, France's congress, suspended its session Friday morning after news of the attack.

France's counterterrorism agency announced that an investigation was opened for murder and attempted murder with a terrorist motive.

The country was on high alert Friday after calls by the militant group Hamas for a global "day of rage," with protests against Israel's airstrikes on the Gaza Strip. The strikes have been relentless for a week in the wake of Hamas' brutal terror attack on southern Israel.

France has the largest population of both Muslims and Jews of any European nation.

In:
• Terrorism
• France
• Stabbing