Patrick Mahomes' season is over after a devastating knee injury took him out of Sunday's game ... with the team just announcing he's torn his ACL.
The Kansas City Chiefs quarterback led his squad against the Los Angeles Chargers ... and, down 16-13 later in the fourth quarter, Mahomes rolled out to the right -- looking to make a play with his legs.
Watch at your own risk ... Mahomes throws the ball away to avoid a tackle for loss -- but his left knee lands awkwardly and gives out.