A bus plunged into a sinkhole on a city street in northwestern China, killing at least six people and leaving four missing, authorities said. Some 1,000 emergency workers and 30 vehicles were sent to the site, the emergency management bureau in the city of Xining said.

A crane was called in to lift the bus above the sinkhole so rescue workers could look for victims. Video apparently shot by security cameras just after the accident showed the bus gradually settling into the hole while people nearby scrambled for safety.

In this image made from CCTV video, a bus plunges into a sinkhole in the center of a downtown street, Monday, Jan. 13, 2020, in Xining, Qinghai province, China. AP

Other video showed the bus tipped more than halfway into the chasm that had opened up at a bus stop just outside a health clinic. Light and smoke were coming to the surface, possibly as a result of the rupture of gas or electricity lines. Workers using backhoes, dump trucks and other equipment excavated earth around the collapse.

The collapse Monday afternoon left 16 people in the hospital. The emergency management bureau said the bus had been raised from the collapsed 860-square-foot section into which it had fallen.

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The hilly city of Xining is the capital of Qinghai province, one of China's poorest regions, sitting atop the Tibetan Plateau.

The expedited building of roads, tunnels, bridges and other infrastructure to keep China's economy strong has often led to corner-cutting on safety, causing fatal workplace and industrial accidents. Mining had also caused instability in the ground in many areas after years of barely restricted mineral extraction.

In 2015, a sinkhole in a northeastern Chinese city swallowed five people waiting for a bus in a dramatic scene that was captured on security video.

The AFP reports that in 2013, five people died when a 33-foot wide sinkhole opened up at the gates of an industrial estate in Shenzhen.