July 24 (UPI) -- The roof of a middle school gymnasium in China's northeastern Heilongjiang province has collapsed, killing at least 11 people, according to state-run news.
The incident happened at about 3 p.m. Sunday at the No. 34 Middle School of Qiqihar City, which is located about 912 miles northeast of Beijing, while 19 people were inside the building, the official state-run news agency Xinhua reported.
Four people were able to escape, leaving 15 others trapped.
The death toll was announced by the incident's rescue command center Monday after the last of the victims trapped were excavated. Four people suffered non-life-threatening injuries, it said.
A preliminary investigation indicates construction workers had placed perlite atop the gymnasium while constructing an adjacent building, and the construction material became heavy as it absorbed recent rainfall, causing the roof to collapse.
Officials of the unnamed construction company have been taken into police custody, the news agency reported.
Such tragedies the result of lax safety regulations and enforcement are not uncommon in China. Last month, 31 people were killed and seven others were injured after a leak of a liquified gas tank at a barbecue restaurant caused a massive explosion.
In April, 29 people were killed and another 21 were seriously injured in a fire at a Beijing hospital that was ignited by sparks from construction work. Most of the victims were patients at the hospital.