Security officials in the northern Mexican state of Tamaulipas say an armed gang has hauled 19 people off a passenger bus.
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The gang allowed 22 other passengers to continue on to the border city of Reynosa.
A Tamaulipas state official who was not authorized to be quoted by name said Monday the mass kidnapping occurred last week.
The official said the victims appear to have been Central American migrants. No relatives have appeared to file missing persons reports.
The official said the case had been turned over to federal prosecutors because it involves organized crime.
The kidnapping recalls the horrors of 2011, when dozens of passengers were hauled off buses by drug gangs in Tamaulipas, killed and their bodies dumped in mass graves.