Ryker Ruelas then caught a 31-yard scoring pass from Joe Callerame to tie the game.
Moments later, Seton started a 94-yard drive that ended with a go-ahead 9-yard run from Callerame.
Ruelas had a game-clinching interception with 1:09 to play after Cashmere drove into Seton territory.
SETON CATHOLIC 42, CASHMERE 35
Seton 14 7 0 21—42
Cashmere 7 7 14 7—35
First quarter
C–Tyler Peterson 17 run (Landon Baker kick)
SC—Ryker Ruelas 84 KO return (Dalton Woods kick)
SC—Joe Callerame 25 from Kolten Gesser (Woods kick)
Second quarter
C—Logan Spies 18 from Rylan Hatmaker (Baker kick)
SC—Ruelas 60 from Gesser (Woods kick)
Third quarter
C—Caed Wilkinson 43 from Hatmaker (Baker kick)
C—Peterson 2 run (Baker kick)
Fourth quarter
C—Isaac Zavala 6 from Hatmaker (Baker kick)
SC—Teddy Wieczorek 30 from Gesser (Woods kick)
SC—Ruelas 31 from Callerame (Woods kick)
SC—Callarerame 9 run (Woods kick)
Rushing
SC—Joe Callerame 7-66, Jacob Williams 15-48. C—Tyler Peterson 24-144, Isaac Zavala 5-39, Trae Smith 6-35.
Passing
SC—Kolten Gesser 14-21-252-1, Callerame 1-1-31-0. C—Rylan Hatmaker 16-23-205-1.