The severity of the injury, which appeared to be to his knee, is not yet known.
Perkins took a hard hit to his left knee and stayed on the ground to be attended to by team medical staff. He waked off the field under his own power, but was limping significantly.
He could been seen having his knee massaged on the sideline and attempting to ride a stationary bike, but head coach Jim Mora told ESPN sideline reporter Kaylee Hartung before the start of the second half that Perkins would not return.
Perkins had carried the ball 11 times for 73 yards before the injury. He led the Pac-12 with 1,575 rushing yards last season.
Second-string running back Nate Starks was ruled out with a head injury before the game, leaving freshman backs Soso Jamabo and Bolu Olorunfunmi as the Bruins’ rushing options.
In addition to Perkins, wide receiver Devin Fuller left the game in the third quarter after taking a hit to the head/neck area. Fuller initially headed to the bench, but was taken to the locker room after being checked out by medical staff. Hartung reported that it seemed doctors were not doing concussion protocol, but rather focusing on his neck.
Linebacker Isaako Savaiinaea, the leading tackler for the Bruins, left the game in the third quarter after a California player landed on his leg. Savaiinaea was later carted to the locker room.
UCLA is one of the most injury-plagued teams in college football. Three defensive starter—linebacker Myles Jack, defensive tackle Eddie Vanderdoes and cornerback Fabian Moreau—are all out with season-ending injuries.