BUFFALO, N.Y. - Buffalo Bills running back Fred Jackson says he expects to be out for about four weeks with a groin injury while C.J. Spiller will reportedly miss the rest of the season with a broken collarbone.

Spiller was carted off in the second quarter of the Bills' victory over the Minnesota Vikings after injuring his shoulder. According to a report from NFL.com, Spiller will have surgery on Monday and is done for the season.

Jackson told WGR radio Monday that doctors gave him that prognosis. 

The Bills will likely have a depleted offensive backfield when they face the Jets on Sunday. Coach Doug Marrone is expected to address the injuries Monday afternoon.