It would come down to an act of desperation to save them. A stick bomb thrown an impossible distance down the narrow passage missed the bolt-throwing marine. It might have seemed unlucky, but instead found a ripe target in the way of a gas-line.
The explosion was immense. Though the consuming fireball was not going to effect the Dark Angel, aside from his power armor adjusting to cool off the additional heat, the blast weakened the surrounding walls and sent tons of rock and earth descending right onto the marine beneath.