Around 30 Chilean students were injured Wednesday, some of them critically, in an explosion caused by Molotov cocktails they were apparently handling inside their school in the capital, authorities said.
Five of the students from the Barros Arana National Boarding School in Santiago were in danger of dying, Health Minister Ximena Aguilera told a news conference.
Police colonel Fernando Albornoz said it was unclear why the devices exploded.
The blast resulted in "various burns to a large number of students who were inside the bathroom," he said.
Local media said the explosion took place during preparations for a graduation celebration.
"The situation is a tragedy," Interior Minister Carolina Toha said.
"Molotov cocktails are weapons," she said, adding that they were not an "acceptable tool for protests."
In recent years, students from the school have often been involved in demonstrations and clashes with police as they demand more resources for public education.