BOISE, Idaho (AP) — A federal judge says a lawsuit brought by a group of Idaho inmates against private prison company Corrections Corporation of America can move forward after finding that the inmates' claims of understaffing and poor management of gangs were plausible.

But U.S. District Judge said two inmates in the group couldn't be part of the lawsuit because they didn't fully use the prison's grievance system for dealing with problems before taking their issues to court. CCA runs the Idaho Correctional Center south of Boise under a contract with the Idaho Department of Corrections.

The inmates filed the lawsuit late last year, contending that poor management and chronic understaffing led to an attack where they were jumped, stabbed and beaten by members of a prison gang.