Employees were working to remove and change the air swivel on the down the hole hammer (DTH) machine. They were using a 60" pipe wrench weighing 60lbs. to loosen the drill steel by over-torqueing the pipe wrench and wedging it against the mast while rotating the drill steel in a counter direction. After some attempts, the DTH operator approached to help Employee 2. The drill then rotated and the pipe wrench contacted the right side of Employee 2's face, knocking him to the ground. The wrench then struck the DTH operator on the hard hat. Both employees were taken to the hospital. The DTH operator was released from the hospital after an evaluation. Employee 2 was hospitalized with multiple fractures to his jaw and cheek bone on the right side of the face.