Nine people were killed and two others remained trapped after the roof of a school gymnasium collapsed in Qiqihar city of northeast China's Heilongjiang province.

Nineteen people were at the gymnasium covering about 1,200 square metres at the No. 34 Middle School in Longsha district on Sunday when the accident occurred.

The municipal search and rescue headquarters said four people escaped, and 15 were trapped.

So far, 13 people have been recovered, with three pulled out without vital signs and six died after treatment failed, the state-run Xinhua news agency reported on Monday.

Rescue efforts are still underway.

A preliminary investigation suggested construction workers illegally placed perlite on the roof while constructing another teaching building adjacent to the gymnasium.

Under the influence of rainfall, the perlite was soaked in water and gained weight, resulting in the roof collapse.

According to local authorities, the gymnasium's walls have a grid structure, and the roof is made of concrete slabs.

An in-depth investigation is ongoing.

Those in charge of the construction company have been taken into police custody, the Xinhua news agency report said.

PTI

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