Rescuers recovered the bodies of four miners on Friday after a gas explosion at a coal pit in Balochistan’s Singidi left a dozen colliers trapped in the mine, the Provincial Disaster Management Authority said.

“Rescue operations are underway in the coal mine in Sanjdi,” Chief Mines Officer Abdul Ghani Baloch said. The operation involves the Balochistan Mines Department, the PDMA, and various volunteer organisations.

Sources said that the bodies were recovered from a depth of 2,000 feet while the trapped miners are located approximately 4,200 feet deep.

A local rescue team began the search for the workers in the private mine on Thursday, before being joined by two teams from Quetta.

“An accumulation of methane gas caused the blast,” said Abdullah Shawani, the head of the province’s mining department, on Thursday.

Pakistan’s mines are known to have hazardous working conditions and poor safety standards, and deadly incidents are not uncommon.

Twelve miners were killed in a gas explosion at the same mine in June last year.