QUETTA: At least two colliers were killed in a gas explosion inside a coal mine in Dakki area of Balochistan, Geo News reported on Monday. Two other miners were trapped inside the mine in the aftermath of the explosion, which caused part of the mine to cave in. Rescue efforts were under way to retrieve the colliers trapped in the mine. At least 20,000 labourers are employed in 2,500 mines across Balochistan, according to government sources. Fatalities in the coal-mining sector in the country are commonplace, highlighting the need for better labour protection.