ORCHARD PARK, N.Y. -- The Buffalo Bills lost running backs Fred Jackson and C.J. Spiller during Sunday's game against the Minnesota Vikings as both were carted off in the first half of the Bills' 17-16 win and didn't return.
Jackson suffered a groin injury, while a source told ESPN NFL Insider Adam Schefter that Spiller broke his collarbone.
Bills coach Doug Marrone said after the game that Spiller will be out "for an undetermined time." The running back is scheduled to have surgery on the collarbone on Monday, a league source told ESPN's Adam Caplan.
Jackson stayed down on the field after a third-and-1 run in which he was stopped short of a first down. Jackson was eventually helped to his feet and walked to the sideline with assistance from center Eric Wood and a trainer.
A cart later took Jackson, with hands covering his face, to the locker room.
Jackson had an MRI on his injured groin Sunday night and will miss one-to-two weeks, according to multiple reports.
Spiller took his first carry of the game 53 yards to the Vikings' 15-yard line but came down hard on his shoulder. He remained of the ground for several minutes before being carted off.
Jackson, 33, is the NFL's oldest running back and the Bills' most-tenured offensive player. Through the first six games this season, Jackson ran 52 times for 227 yards and one touchdown. He added 30 catches for 245 yards and a touchdown.