Mercy Award in Crystal Refinery

[The Atomic Ass]

How does one distract the guards in the rooms with the green and blue keys? They don't exit the rooms when I detonate a bomb right outside of the them, and inside is too close.

[The Atomic Ass]

Oh, never mind, for some reason the top guard doesn't respond to bombs from the top doorway. :/

[The Cake Is A Spy !]

Got the same problem, how do you get this achievement ?

EDIT: Well, actually you can blow the rocks behind the rooms and bombs that explode behind the wall of the room will attract the guards