The Dallas Cowboys placed defensive tackle Jay Ratliff and right guard Mackenzy Bernadeau on the active/physically unable to perform list Sunday.
The team also signed offensive tackle Demetress Bell.
Ratliff and Bernadeau both have hamstring injuries.
Bell, who played for the Philadelphia Eagles last year, will start training camp on the active/non-football injury (NFI) list.
Also, the Cowboys signed quarterback Alex Tanney to add depth behind starter Tony Romo, and placed center/guard Ryan Cook, long snapper Louis-Philippe Ladouceur, guard Ronald Leary, guard Nate Livings and wide receiver Lavasier Tuinei to the NFI list.
All the players can be activated anytime before the start of the season.