Four coal mine workers were killed on Sunday when a part of a mine located in the Sanjadi area of Quetta collapsed, officials said.

Initial investigations reveal that the mine collapsed due to a gas explosion, Chief Inspector Mines Iftikhar Ahmed told reporters.

Take a look: Life of a coal miner in Punjab

Four bodies have been recovered from the debris, he said, adding that the explosion also affected nine others — six of whom have been treated after provision of first aid, while three are under treatment.

All the killed labourers hailed from Swat, he added.

The slain labourers were identified as Mohammad Rahman, Yar Khan, Badsha Wazir and Ghulam Mohammad.

Over 27 miners were killed last month in two coal mine incidents in the province. The provincial government had set up a four-member committee to investigate the coal mine accidents. However, no details on the progress of the committee or the report were made available as yet.