A principal and five other managers at a school in northwestern Shaanxi Province, where 11 female students died of carbon monoxide poisoning on Tuesday, have been detained for investigation.

The procuratorate of Dingbian county, where the school is located, has also begun an investigation to determine whether managers failed to prevent the accident, said an official with the county's publicity department, who declined to give his name.

Altogether 12 girls, all fourth graders, were poisoned after using a charcoal heater to warm their dorm room at the Duiziliang School in Yulin City.

Eleven died at the hospital. The sole survivor is still being treated at the Dingbian County Hospital. A doctor said she was in stable condition.

Police believe a quilt fell on to the stove during the night. It caught fire and then ignited coals being stored under one of the girl's beds. As the coals smoldered, the students were poisoned by gases.

A teacher, who asked to remain anonymous, told Xinhua that the dorm room usually held 12 students. Heaters and charcoal were provided by the school.

"The girls are boarding students. Their homes are at least two kilometers from the school. They have a self-study class in the evening and only stay at home on weekends," said the teacher.

Heart-broken parents of the dead students gathered at the school to meet with the local government.

A middle-aged man, who only gave his surname Wang, said his 10-year-old daughter died in the accident.

Wang, who worked as a hotel chief in Ordos City of the neighboring Inner Mongolia Autonomous Region, rushed back home on Tuesday afternoon after hearing the news.

Looking at his daughter's body, Wang could not believe his girl was gone. He blamed himself for spending little time with her.

"I told myself she just fell into sleep and would wake up later," said the man through his tears.

Soon after the accident, the Ministry of Education (MOE) ordered boarding schools across the country to conduct safety checks for carbon monoxide poisoning and fire risks.

Night watches in student dormitories must be strengthened and schools still using coal furnaces are required to install carbon monoxide alarms as soon as possible or replace the furnaces with central heating systems, it said.

School authorities must also educate students on how to prevent carbon monoxide poisoning for the students, the MOE added.

(Xinhua News Agency December 3, 2008)