QUETTA, Pakistan — Police in Pakistan say a methane gas explosion in a coal mine has killed at least four miners and trapped 13 others.

Local police official Wajeet Khan says the blast happened Sunday in the village of Sanjdi, about 50 kilometers (30 miles) east of Quetta.

He says rescuers have retrieved four bodies and that 13 other miners are missing and feared dead, with rescue operations hindered by the gas leak.

Cave-ins and other mining accidents in Pakistan are often attributed to the poor enforcement of safety regulations.