The primary school stampede that left 41 children in hospital in northwest China on Monday was triggered when a girl bent down to pick up a lost shoe on a flight of stairs, the school head told Xinhua Wednesday.

The girl, Madina, 8, was knocked over and buried under dozens of children on the 1.5-meter-wide stairwell of the second floor of the four-storey building, said Aytursun Metniyaz, principal of Aksu No. 5 Primary School, in Xinjiang Uygur Autonomous Region.

Hundreds of other children behind her kept pushing, unaware of the accident, as they hurried to the playground at 11:55 a.m..

Madina was the most severely injured of the 41 children admitted to the No. 1 People's Hospital of Aksu. A total of 123 children were taken to the hospital.

Madina is still being treated in the intensive care unit, but is out of danger, according to hospital staff. "She can even sit up and take fluids," said a doctor, who declined to give his name, Wednesday.

Madina's mother, Mayrgul, has been at the hospital since the accident. "When I first came and saw my girl, she couldn't recognize me. I'm so worried." The mother and daughter like many ethnic Uygurs have only one name.

Aygul, a teacher who was guiding the children to the playground, saw Madina being crushed. She tried to pull the girl up, but was pushed over herself.

"It turned chaotic in a second," Aygul said. About 10 teachers ran to the stairwell and restored order in minutes.

With hundreds of children piled up, crying and shouting, it could have been much worse, said a teacher, who joined the rescue but declined to give his name.

The school has repaired thick steel columns of the stair handrail that were broken and twisted in the accident.

Rezya Turusun, an 8-year-old second grader, recalls stumbling, falling on an older child and being buried under five or six children. "It was so frightening, everybody was crying."

Rezya is in the hospital under medical observation for breathing difficulties, but she said she felt better and wanted to return to school.

Seven less severely injured children were receiving psychological counseling at the hospital from school psychiatrist Asya. "Most children were frightened, even traumatized, after the stampede. But they are gradually calming down," Asya said.

Principal Aytursun Metniyaz said the school attached great importance to safety and deployed teachers to guide students at each stairwell. "It reminded us that we can never be careful enough"

The incident in the school, which was founded in 1965, with 1,892 students and 122 teachers, is the second school stampede in Xinjiang this year.

On March 22, a stampede at a primary school in the regional capital Urumuqi killed one child and injured three others.

In 2005, a stampede in another primary school in Aksu, about 1,000 km southwest of Urumuqi, left a boy dead and 64 injured when students were rushing outside to attend a flag-raising ceremony in the playground.

In 2009, a stampede in a secondary school in central China's Hunan Province left eight students dead and 26 injured. The head of the educational bureau of Xiangjiang City, where the school is located, was sacked following the tragedy and the schoolmaster was jailed for 18 months after being convicted of dereliction of duty.