The New England Patriots placed linebacker Jerod Mayo and running back Stevan Ridley on injured reserve Thursday and signed offensive lineman Chris Barker and running back Jonas Gray from the practice squad to the 53-man roster.

Mayo and Ridley suffered knee injuries on Sunday during the Patriots’ 37-22 win over the Buffalo Bills in Orchard Park, N.J.

For Mayo, it’s the second significant injury in the past two seasons. Last year, he injured a pectoral muscle in October that kept him off the playing field for the remainder of the 2013 season.

Ridley was leading the Patriots in rushing (4-2) in the first six games this year with 340 yards on 94 carries and two touchdowns. Shane Vereen, who has 216 yards rushing this season, will take over bulk of the carries for the offense.

Barker was released by the Patriots on Sept. 1 and signed to the practice squad two days later. He spent last season on the New England roster, playing most only special teams in four games.

Gray was signed by the Patriots on Jan. 8. An undrafted free agent of the Miami Dolphins in 2012, Gray spent his first season on the physically unable to perform/non-football injury list in 2012 and was released by Miami on Aug. 31, 2013. He then was signed to the Baltimore Ravens’ practice squad last September.

This year, he was released by the Patriots on Aug. 30 and signed to the practice squad on Sept. 1.