ARRAS, France (AP) — A man of Chechen origin who was under surveillance by French security services over suspected Islamic radicalization stabbed a teacher to death at his former high school and wounded three other people Friday in northern France, authorities said.

France raised its threat alert to its highest level, and the attack was being investigated by anti-terrorism prosecutors amid soaring global tensions over the . It also happened almost three years after another teacher, Samuel Paty, was near a Paris area school.

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