What is the origin and context of use of 'fire in the hole'?

"Fire in the hole" is a warning phrase that originated in military and mining contexts. Its primary purpose is to alert others in the vicinity that an explosion is imminent or has been initiated. In military usage, "fire in the hole" is shouted to warn soldiers or personnel that a grenade or explosive device is about to be detonated. It's crucial for the safety of everyone nearby, as it gives individuals a chance to take cover or move away from the blast zone.