URUMQI - One child was in critical condition and six others were severely injured after a stampede occurred Monday at a primary school in Northwest China's Xinjiang Uygur autonomous region, local officials said.

The accident happened at the No 5 Primary School in Aksu City, about 1,000 kilometers from the capital of Urumqi, as students were rushing down a flight of stairs near lunchtime.

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Some students in the lead fell and those in the rear continued stepping on each other and pushing out the stairway handrails, witnesses said.

Students were crying and frightened, said Zhang Yuping, an official with the city's first-aid center that sent five ambulances to transport students.

A total of 123 children have received medical check-ups and 41 were admitted to Aksu's No 1 People's Hospital, according to the emergency-response office of Aksu.

One child suffered serious injuries to his internal organs and is in critical condition, six pupils were badly injured and 34 others received light injuries, officials said.

No deaths have been reported.

The regional government has set up a team of investigators, headed by a vice chairman of Xinjiang, to fly to Aksu. Heavy fog, however, has delayed their departure.

The school has more than 1,800 students.

Authorities have begun an investigation into the stampede.

In 2005, a stampede in another primary school in Aksu left a boy dead and 64 injured when students were rushing outside to attend a regular flag-raising ceremony on the playground in the morning.

In 2009, a stampede in a secondary school in central China's Hunan Province left eight students dead and 26 injured. The chief of the educational bureau of Xiangjiang City, where the school is located, was sacked following the tragedy and the schoolmaster was sentenced to prison for 18 months.