I was conducting our monthly Short Range Match at Cedar Ridge Range in San Antonio, Texas, when I heard a loud pop instead of a bang as a competitor was completing a stage. I looked up and saw the safety officer walking toward me with the shooter who was holding his left hand with blood pouring through his fingers. His pistol was lying on the ground where it had fallen from his hand.
The shooter's pistol had failed to go into battery, and the shooter had aggressively hit the back of the slide with his left palm in an attempt to clear the stoppage. As he did this, the fingers of his left hand went forward over the top of the slide just as the round detonated in the open ejection port.
Fragments of brass severely cut his left index and middle fingers. After examining the shooter's injured left hand, a doctor at the scene determined he was not seriously injured and only had some bloody, but not serious cuts.
When we retrieved and examined the pistol, we realized the remains of the detonated round were still in the ejection port. It was apparent that the round had nosedived into the feed ramp and, in doing so, it literally positioned the primer exactly over the extractor. When the shooter slammed the slide forward with his left hand, the extractor crushed the primer causing the 9mm round to detonate.
In my classes, I teach the proper response to a click instead of a bang is to tap the magazine and rack the slide — tap rack. This will often clear the malfunction. If it does not, the proper response is to lock the slide back, aggressively strip the magazine out, then reload the pistol.
If it does not fire after reloading, you probably have a broken pistol that's not going to be fixed easily on the spot. If you are under fire, the proper response at that point is to aggressively depart the area or take other necessary action.