The Associated Press reported that Kolb stumbled awkwardly and had trouble standing. Visibly frustrated, he departed for the locker room with a trainer and did not return to the practice field.
Even if Kolb is only out for one or two practices, his injury effectively swings the door wide open for rookie EJ Manuel to take control of the Bills offense.
Manuel has been impressive through the first week of training camp, but Kolb has still seen the majority of first-team snaps. Ideally, the Bills would most likely want to continue to ease Manuel into the starting role, but Kolb's injury could change that.
The Bills open their preseason in Indianapolis on Aug. 11, and if Kolb remains out of practice into next week, Manuel could see the bulk of the action in that game.
With Kolb out of the remainder of Saturday's practice, the Bills were down to Manuel and undrafted rookie Jeff Tuel at quarterback. They have an open spot on their 90-man roster, which could be used to sign another quarterback if they anticipate Kolb missing any stretch of time.