A fire in a school dormitory in Guyana that killed 19 children was lit by a student after school authorities confiscated her cell phone, police said on Tuesday.

The children, mostly Indigenous girls, died around midnight on Monday, most at the scene.

“A female student is suspected of having set the devastating fire because her cellular phone was taken away by the dorm’s mother and a teacher,” police said in a statement.

David Adams, the mayor of Mahdia, the town where the school is located, earlier confirmed the student’s alleged involvement to Reuters and said she was not injured in the fire.

He added he could not confirm whether the student was in government custody. The police statement did not mention an arrest.

Some students told investigators they were awakened by screams and saw fire and smoke in the dorm’s bathroom area, police said.

The government pathologist who conducted post-mortems on six bodies late on Monday listed their cause of death as smoke inhalation and burns, police added.

Thirteen sets of remains had been moved to the capital Georgetown for DNA identification. Nearly 30 other children were hospitalised.

Minister of Education Priya Manickchand earlier declined to discuss the student’s alleged involvement.

Asked about allegations that the dormitory was not outfitted with a modern fire alarm system and that students were not trained in fire drills, Manickchand told Reuters “all of that is under investigation and a report will be issued once that is done. What must come of this is improvement across the sector.”

Burn specialists, psychiatrists and other medical staff were attending to injured children and their families, she added.

The youngest of the fatalities was the five-year-old son of the dormitory’s caretaker. All other victims were girls, and included several siblings and at least one set of twins.

President Irfaan Ali met with some parents of the dead on Monday after visiting Mahdia’s hospital, and declared three days of national mourning.