Peterson was running through the Raiders defense when he was caught by safety Michael Huff. It appeared that Peterson got his ankle caught underneath him, and he needed assistance to get off of the field. The trainers are currently working on his left ankle. At this point, the trainers are working on him, so we're not sure how bad it is, but it looked bad on the replay.
As it stands now, Peterson's replacement on the field will be Toby Gerhart, but while Gerhart is a nice back, he's not Percy Harvin or anything.
As soon as we get further word on Peterson's injury, we will pass it along to you. For now, we're just keeping our fingers crossed and hoping that it's not as bad as it initially appeared.
Video appears after the jump.