Four workers suffered injuries, two of them seriously, when the roof of a mine partially collapsed at Putki Balihari area in Dhanbad district on Thursday.
The mine falls under Bharat Coking Coal Limited (BCCL), a subsidiary of Coal India Limited.
A senior district official said the four contractual workers were taking cable to a shaft of the hydro mines in lift when a part of the roof suddenly caved in trapping them.
The four were rescued and taken to a hospital where the condition of two of them was stated to be serious, the official said.
The two seriously injured were now under treatment at Central Hospital, Dhanbad while the other two were being treated at a local hospital in the neighbourhood of the mines and were out of danger, the official added.
The cause of the collapse was being looked into, the official said.