The tragedy occurred at about 2:00 p.m. on Wednesday, when about 300 square meters of rock and earth tumbled into Shihuitang quarry, in Baishuiwan Village of Anji County, Huzhou City, burying four workers.

The biggest rock weighed about one ton, according to local sources.

Two of the victims died in hospital and two are still being treated but are described as out of danger.

The injured are 42-year-old Xu Liwen and 50-year-old Wang Chengfu, both of Anji County. The identities of the two dead workers have not been released.

The quarry was privately owned and legally operated, said a local government source.

The owner, Fu Jihua, had offered compensation of 30,000 yuan (3,846 U.S. dollars) to the families of each of the dead workers.

The cause of the accident is under investigation.

Anji County government has ordered suspension of 33 quarries and mines to allow for safety inspections.