Scary moment on the ice ... a pro hockey player was knocked out cold during a fight Tuesday -- and had to be rushed to the hospital to make sure he was okay.
The scrap all went down in the American Hockey League (the NHL's developmental league) during a game between the Hershey Bears and the Charlotte Checkers in Pennsylvania.
Bears center Kale Kessy locked horns with Checkers D-man Derek Sheppard in the 2nd period -- and that's when things escalated QUICKLY.
You can see in video of the tilt .