The inmates, William Morales, 28, of Jersey City and David Gast, 28, of Wisconsin, were found January 6 chiseling into the cinderblock wall of their cell in a medium-security portion of the prison near Newark International Airport.

Both are serving time for manslaughter and now face attempted escape charges, which could add five years each to their sentences.

Corrections officials would not release details of the escape attempt, but a published report, citing an unnamed source, said the pair had made a nearly 4-foot hole in the cell wall.

Just before midnight on New Year's Eve, two other inmates broke out of their locked cell in a disciplinary unit, using a hacksaw blade, but were caught before they could leave the grounds. They, too, face attempted escape charges.

Two other inmates from Jersey City who walked away from a minimum-security dormitory at the prison remain at large.

Eduardo Diaz, 37, who was doing time for a parole violation, and Frederick Martinez, 38, serving five years for aggravated assault, slipped away from the prison Dec. 23, and were spotted walking on Route 78 by a corrections officer in the prison's tower.

Police were unable to capture the men. Corrections officials said the pair were placed in the low-security area because they had served at least half their sentences, and were incarcerated for less serious crimes.