Scary moment in the NHL on Tuesday ... Chicago Blackhawks winger Jujhar Khaira was knocked out after taking a violent shoulder to the face -- and he was eventually hospitalized.
The horrifying scene all went down in the second period of the Hawks' game against the Rangers in Chicago ... when Khaira was blindsided by New York star Jacob Trouba.
You can see in footage of the play, Khaira's head slammed hard off the ice after he took the hit ... and he was immediately knocked unconscious.