ORCHARD PARK, N.Y. -- Buffalo Bills coach Dick Jauron is concerned about the severity of leg injuries sustained by linebackers Kawika Mitchell and Marcus Buggs, further depleting the team's already banged-up defense.

"I'm not optimistic about those injuries," Jauron said after Mitchell and Buggs were hurt during Sunday's 6-3 loss to the Cleveland Browns. "We'll find out more tomorrow and, clearly, we'll have to do something if those turn out to be serious."

Mitchell was shifted from the weak-side position to start at middle linebacker this past week in place of Buggs. And Buggs had started the past three games in the middle only because starter Paul Posluszny is still out with a broken left arm.

Mitchell was carted off the field after hurting his right knee early in the second quarter. Mitchell was attempting to tackle Browns running back Jerome Harrison on a sweep left when he was bowled over by two Browns linemen. Mitchell was on the field for several minutes and wasn't able to put any weight on his right leg as he was lifted onto the cart.

Buggs was carted off after hurting his left leg while covering on a punt return late in the third quarter. Jon Corto finished the game in place of Buggs, leaving the Bills with only one experienced healthy linebacker on their roster, starter Keith Ellison.

The Bills also played their second consecutive game without starting safeties Donte Whitner (right thumb) and Bryan Scott (ankle).

While starting left tackle Demetrius Bell returned after missing one game because of a groin injury, starting right tackle Jonathan Scott didn't return for Buffalo after hurting his ankle during the third quarter.

Browns defensive end Kenyon Coleman hurt his groin and didn't return.