A judge in Mexico has ordered the detention of 16 guards and officials at a prison near the U.S. border where the brutal Zetas drug cartel orchestrated a mass tunnel escape of more than 130 inmates.

The judge ruled Wednesday that the prison director, two top aides and 13 other prison employees be held for 40 days under a form of house arrest, pending possible charges.

The judge said there was credible evidence that prison employees aided the escape.

On Tuesday, authorities detained two of the escapees following a shootout with police.

Police were investigating whether the prison break might be linked to seizures of empty passenger buses in the region that could have been used to pick up the escapees.