Terrorists in explosive vests have reportedly threatened Pakistan train passengers' lives if officials refuse to release imprisoned militants.

The BLA is one of the largest militant outfits demanding independence for Balochistan. It is designated as a terrorist group by Pakistan as well as the US.

Mehboob Hussain was riding the train home on Tuesday when the tracks under the front car exploded. In the depths of central Pakistan's Bolan Pass, a pocket of wilderness so remote that there is no internet or mobile network coverage, the nine-coach Jaffar Express ground to a halt. Then the bullets started flying.