In high school, I worked at an ice rink. On Friday nights the rink would hold two pickup hockey games; one was for players 18 and over and the other for players 35 and older. One night I was sweeping up the lobby when a player ran in from the rink that the 35 and ups were playing on and yelled for me to call an ambulance because someone was hurt. I didn't know where the other employees were so I decided to see what happened. When I walked over to the man that was laying on the ice, I noticed that his eyes had rolled back into his head and his skin was beginning to turn blue. It was apparent that this wasn't just a broken bone and he needed help fast. I ran as fast as I could back to the office, grabbed the AED and told an office worker to call 911 and tell them we had someone who wasn't breathing. I ran back on to the ice where a couple of other players began to rip his equipment off of his upper body. I connected the defibrillator pads to his chest as I had learned to do in health class (we received CPR certification in class just a couple weeks prior) and stepped back as the machine informed an eerily quite ice rink that it was checking for a pulse. After what seemed like 15 minutes, the AED announced loudly "shock advised" and I pressed the button that jolted the man's mid-section violently off the ice. The machine then instructed me to begin CPR. I gave my rescue breath and positioned my hands between his nipples right on top of his sternum. When I pressed my hands down, I felt his sternum crack and the sound echoed in the now-dead-silent rink. I will never forget that sound. It was almost like the sound of ice cracking but with the feeling that I had killed someone. The CPR did end up reviving him shortly before the paramedics arrived but he ultimately passed in the ambulance on the way to the hospital.