Four miners were killed and three injured on Friday night following an explosion at a coal mine in Balochistan's Sara Gurgai area, situated on the outskirts of Quetta, chief inspector of the province's mines and minerals department, Abdul Ghani, said.

The official said that a massive explosion in the mine had left seven miners trapped, of which four died and three were shifted to the trauma centre of Civil Hospital, Quetta.

He said the rescue operation was launched last night and the process of identifying the deceased was under way.

Meanwhile, he added, the coal mine where the explosion occurred had been sealed.

The cause of the blast was yet to be determined, he said.

According to Ghani, the latest incident was the second mining accident reported in the province this year and a total of eight miners had died in the two incidents.

Separately, Pakistan Central Mines and Labour Federation Secretary General Lala Sultan told Dawn.com that over 104 coal miners had lost their lives in mining accidents in the province the previous year.