The Buffalo Bills are hurting at running back.

Big offseason acquisition LeSean McCoy is expected to be sidelined a few more weeks with a hamstring injury. Fifth-round rookie surprise Karlos Williams, who is averaging an impressive 5.4 yards per carry this season, suffered a concussion in last week's loss to the New York Giants. His status is questionable at the moment.  As a result, the Bills are working out a handful of running backs, including Trent Richardson.

Desperate times calls for desperate measures.  

Ian Rapoport of NFL.com reports that Richardson and fellow ex-Indianapolis Colt Daniel Herron will be working out for the Bills this week. John Wawrow of The Associated Press tweets that Alfonso Smith will be present as well.

Recently released ball carrier Bryce Brown is another emergency option should McCoy and Williams be unable to go. At this moment, Boobie Dixon and Cierre Wood, who was just promoted from the practice squad, are the only healthy running backs on the 53-man roster.

Of all the options mentioned, Herron is likely the best choice. He appeared in all 16 games for the Colts last year, carrying the ball 78 times for 351 yards (4.5 YPC) and one score. He also hauled in 21 passes for 173 yards. While Herron's skillset doesn't translate to feature back duties, he could be effective in limited action and is likely the most attractive option for the thinned out Buffalo backfield at the moment.

We'll keep you updated as Rex Ryan and the Bills make their decision.