An MLB umpire left a game at Coors Field on Monday night mid-inning — never to return — in a truly odd situation. 

The weird scene occurred during the top of the third inning of the Cubs-Rockies game when home plate umpire Brian O’Nora paused play and proceeded to run into the dugout. 

The action was halted for 15 minutes while second base umpire Tom Hanahan took over behind the plate.

When play resumed, the game finished with just three umpires, and O’Nora never went back behind the plate. 

An official explanation never came, but ESPN reported O’Nora was not feeling well and is not expected to work Tuesday night’s game.

“He was sick. I think he was throwing up or something,” Rockies starter Kyle Freeland told the Denver Post after the game. “It’s never happened to me. I can’t recall ever having a home plate umpire get knocked out, like with a foul ball or anything like that, and have to switch.

“Not while I’m pitching at least.”

The Cubs went on to win the game, 5-4, and they entered Tuesday night two games up for the second wild-card spot in the National League.

O’Nora, who has been an umpire in the majors since 1992, has worked three different All-Star Games (2000, 2010, 2019) and one World Series (2012).