Video footage shared online shows the bus falling into a gaping sinkhole while waiting at a stop in the city of Xining, Qinghai province. Once the bus is in the sinkhole, only the rearmost portion of the vehicle is visible. The footage shows people who were waiting to board the bus running for their lives when the collapse takes place. Other footage shared online shows rescuers trying to pull people out of the bus and sinkhole, which authorities estimate was about 32 feet in diameter.
According to multiple reports, rescue crews worked throughout the night Monday to free the passengers. Some business owners even said they tried to break the bus windows to help the passengers escape.
The bus was pulled out of the hole Tuesday. Chinese authorities are still investigating the incident.
Sinkholes typically occur due to erosion or underground water, Conserve Energy Future reports.
“There is water continually seeping in between the mud, rocks and minerals, as it makes its way down to the ground water reservoirs. As this happens, the water slowly erodes the rocks and minerals. Sometimes the flow of water increases to a point when it washes away the underground structure of the land. And when the structure becomes too weak to support the surface of the earth, it collapses and opens up a hole,” the website explains.
This is not the first sinkhole incident to have taken place in China. Subway trains in the southeastern city of Xiamen were swallowed by a sinkhole in December, and three people fell into a sinkhole near a subway in the city of Guangzhou that same month. In 2013, a sinkhole caused a building complex in the southeastern city of Shenzhen to collapse. Five people were killed in the Shenzhen collapse.