Frustrations grow among migrants stuck at Mexico-US border Frustration is growing among more than 1,600 Central American migrants penned for more than a week inside a disused factory turned shelter in the northern Mexico border city of Piedras Negras

MEXICO CITY -- Frustration is growing among more than 1,600 Central American migrants penned up for more than a week inside a disused factory turned shelter in the northern Mexico border city of Piedras Negras.

Joe Rivano Barros, of the Texas-based refugee advocacy group Raices, said emotions were running high Wednesday after police and soldiers guarding the shelter didn't allow migrants to leave to go to nearby shops.

Rivano, who was outside the shelter, said people were frustrated and confused because they felt trapped and no one was telling them what was happening.

Coahuila state security officials did not respond to requests for comment. In a statement, they conceded there had been complaints by some migrants and said they would be attended to.

The majority hope to cross the border to request asylum in the U.S.