URUMQI -?Four people remain missing after a coal shaft below a building collapsed in Xinjiang Uygur autonomous region, Northwest China, early Tuesday morning, local authorities said.

At around 4:30 a.m. in Shuimogou, a district in the regional capital of Urumqi, a shaft managed by Badaowan Coal Mine caved in, causing the building above it to collapse, leaving seven people trapped. The seven people were in a police office in the building at the time of the incident, according to the regional committee of the Communist Party of China.

Three people have been extracted, so far. They remain under observation in hospital and have been described as in a stable condition.

Rescuers continue to search for the missing.

Badaowan Coal Mine is no longer an operational mine, having stopped production before the incident.