Terrifying scene on the NHL ice Tuesday ... a referee needed to be taken away on a stretcher after he was hit in the head in an accidental collision with a player.
The scary moment all went down just before the Kings vs. Coyotes preseason game in L.A. ... when Arizona center Liam O'Brien ran into linesman Ryan Gibbons.
Video of the play showed O'Brien's shoulder went right into Gibbons' jaw ... causing the ref to immediately crumple to the ice in pain.