Coahuila state authorities say about 70 of the 1,676 Central American migrants confined to an improvised shelter in the Mexican border city of Piedras Negras have applied for jobs in Mexico.

Most migrants are only allowed to leave the shelter under police escort to visit a store. About a dozen per day are allowed out to file asylum claims at the U.S. border town of Eagle Pass.

The migrants can't leave because they didn't have Mexican humanitarian transit visas. About 1,000 of the migrants have applied for the visas. Only about 400 have been approved so far.

Authorities said Monday 22 minors have been taken to other shelters, and 58 migrants have asked to return to their home countries. A police force guards the shelter at an unused factory complex.