BEIJING – The concrete roof of a school gymnasium collapsed in China’s Qiqihar city on Sunday, killing 11 people.

A group of young girls were playing netball when the incident happened.

The illegal stacking of materials on the roof may have caused the cave-in, said the authorities.

Initially, 15 people were trapped underneath the rubble, and state media learnt at 10am local time on Monday that the authorities had pulled out the last remaining person, a student, who had no vital signs.

The collapse at the No. 34 Middle School in Longsha District in Qiqihar, located in north-east China’s Heilongjiang province, was reported at 2.56pm local time on Sunday, according to the provincial fire and rescue department, Xinhua said.

A female volleyball team was training in the gymnasium when the incident happened, a father told China Youth Daily as he waited anxiously at the local hospital for news of his 16-year-old daughter.

“The team... had just returned to the school a few days ago after a competition out of town,” an eyewitness told state radio. It was not immediately clear if the victims included adults.

There were 19 people at the gymnasium, with four managing to escape, said the authorities.

In a video that went viral on social media, an angry father complained that the government sent the police to keep watch on parents but did not send anyone to provide an update to the anxious families about their children.

“They tell me my daughter is gone, but we never got to see the child. All the children had their faces covered with mud and blood when they were sent to the hospital. I pleaded, please let me identify the child. What if that wasn’t my child?” the man said.

An overhead aerial view of the scene from social media pictures showed a completely collapsed roof with rescue workers in the gym next to large boulders of concrete.

Other pictures showed large cranes hoisted on the side of the school building as rescue efforts were still ongoing.

The region and several parts of China had heavy rain this past weekend, causing flooding and damage in some areas.

A preliminary investigation found that construction workers illegally placed perlite, a mineral with high water content and can absorb water, on the roof of the gymnasium during construction of a teaching building adjacent to the gymnasium, Xinhua reported.

Under persistent rain, the perlite soaked up water and gained weight, resulting in the roof collapse, state media said.

The accident was condemned in an editorial by The Beijing News, a party-owned newspaper, which criticised the lack of construction supervision.

“Only by truly respecting construction norms, respecting safety, and strengthening the supervision and management of the construction process can we avoid repeating the mistake,” it wrote.

An in-depth investigation is ongoing and individuals in charge of the construction company have been taken into police custody, Xinhua said. REUTERS